Search

Search Results

• 31. [Article] Broadening the horizons of inland fish-farming in the African economy

  Research Paper

  Citation × Citation Citation Abstract Copy Title: Broadening the horizons of inland fish-farming in the African economy Author: Tazoacha, Francis Research Paper Title: Broadening the horizons of inland fish-farming in the African economy Author: Tazoacha, Francis Research Paper Close

• 32. [Article] The influence of air and soil temperatures on the growth and development of Easter lily, Lilium longiflorum, during different growth phases

  Greenhouse-grown, September-harvested Lilium longiflorum cv. 'Nellie white' bulbs were used to determine temperature requirements during 5 pre-bloom and 1 post-bloom phases of development each of 1 month's ...

  Citation × Citation Citation Abstract Copy Title: The influence of air and soil temperatures on the growth and development of Easter lily, Lilium longiflorum, during different growth phases Author: Wang, Yin-Tung Greenhouse-grown, September-harvested Lilium longiflorum cv. 'Nellie white' bulbs were used to determine temperature requirements during 5 pre-bloom and 1 post-bloom phases of development each of 1 month's duration. Plantes were subjected to 3 air temperatures(24°day/ 18°C night, 18°/13° and 13°/10°) in combination with soil temperatures at 30°, 24°, and equal to or lower than ambient air temperature during each growth phase and evaluated by growth analysis at the termination of each phase. This study has substantiated that top growth needs high air temperature and daughter scale initiation and filling require high soil temperature. An air and soil temperature of 24°C was required for rapid flowering, leaf unfolding and stem elongation but at the expense of reserves in mother scales. Air temperature approaching 18°/13° during the month prior to anthesis favored maintenance of mother scales. Growth of daughter scales during the pre-bloom period was directly related to soil temperature rather than air temperature with 30° soil temperature being no better than 24°. Soil temperature had no effect on flower bud expansion after buds-visible stage, air temperature being the determining factor thereafter. Growth of the flower bud, leaf unfolding rate or stem elongation were of equal value in monitoring crop growth rate and status. Soil temperatures approaching 24°C. favored scale primordia initiation, regardless of air temperature. Daughter meristem diameter, as well as the rate of scale primordia initiation decreased progressively from daughter bulb appearance toward anthesis of the mother axis. High soil temperatures also reduced daughter bulb apex diameter during early growth phases. Since prevailing air and soil temperatures in the commercial lily growing sites are below those required for maximum growth and development of above- and below-ground organs during the pre-bloom period, it is concluded that air temperatures alone are adequate in monitoring field crop status and predicting ultimate yield potential during this period. Title: The influence of air and soil temperatures on the growth and development of Easter lily, Lilium longiflorum, during different growth phases Author: Wang, Yin-Tung Greenhouse-grown, September-harvested Lilium longiflorum cv. 'Nellie white' bulbs were used to determine temperature requirements during 5 pre-bloom and 1 post-bloom phases of development each of 1 month's duration. Plantes were subjected to 3 air temperatures(24°day/ 18°C night, 18°/13° and 13°/10°) in combination with soil temperatures at 30°, 24°, and equal to or lower than ambient air temperature during each growth phase and evaluated by growth analysis at the termination of each phase. This study has substantiated that top growth needs high air temperature and daughter scale initiation and filling require high soil temperature. An air and soil temperature of 24°C was required for rapid flowering, leaf unfolding and stem elongation but at the expense of reserves in mother scales. Air temperature approaching 18°/13° during the month prior to anthesis favored maintenance of mother scales. Growth of daughter scales during the pre-bloom period was directly related to soil temperature rather than air temperature with 30° soil temperature being no better than 24°. Soil temperature had no effect on flower bud expansion after buds-visible stage, air temperature being the determining factor thereafter. Growth of the flower bud, leaf unfolding rate or stem elongation were of equal value in monitoring crop growth rate and status. Soil temperatures approaching 24°C. favored scale primordia initiation, regardless of air temperature. Daughter meristem diameter, as well as the rate of scale primordia initiation decreased progressively from daughter bulb appearance toward anthesis of the mother axis. High soil temperatures also reduced daughter bulb apex diameter during early growth phases. Since prevailing air and soil temperatures in the commercial lily growing sites are below those required for maximum growth and development of above- and below-ground organs during the pre-bloom period, it is concluded that air temperatures alone are adequate in monitoring field crop status and predicting ultimate yield potential during this period. Close

• 33. [Article] Effect of cereal companion crops on the establishment of red fescue (Festuca rubra L.) for seed production

  Some perennial grass seed crops such as red fescue (Festuca rubra L.) do not produce a profitable seed crop during the first growing season. The present establishment method in Oregon for red fescue seed crops ...

  Citation × Citation Citation Abstract Copy Title: Effect of cereal companion crops on the establishment of red fescue (Festuca rubra L.) for seed production Author: Chastain, Thomas G. Some perennial grass seed crops such as red fescue (Festuca rubra L.) do not produce a profitable seed crop during the first growing season. The present establishment method in Oregon for red fescue seed crops generally entails spring planting which does not satisfy vernalization requirements for seed production in the year of planting. This establishment procedure relies on the amortization of establishment costs over the seed producing life of the stand. In Europe, perennial grass seed crops are often established with annual companion crops such as winter rape, flax, peas and cereals. Companion crops provide income in the year of establishment, thereby increasing the profitability of the seed production venture over the life of the stand. However, the companion crop competes with the grass seed crop for light, soil moisture and nutrients which often causes unsatisfactory establishment. The primary objective of this study was to determine the feasibility of establishing red fescue with cereal companion crops in Oregon's Willamette Valley. The second objective was to examine the influence of cereal companion crops, cultivars and row spacings on the growth and environment of red fescue. This was investigated to identify companion cropping methods that would be the least competitive with the establishing seed crop. The third objective was to evaluate the effect of companion cropping on subsequent red fescue seed production and income relationships over a two-year period. Two experiments were initiated in October 1982 and October 1983 at the Oregon State University Hyslop Crop Science Field Laboratory. 'Pennlawn' red fescue was established with two winter wheat cultivars, 'Hill 81' and 'Yamhill1, and two winter barley cultivars, 'Hesk' and 'Scio', as companion crops. Cereal companion crops were drilled in 15-, 30-, 45-, and 60-cm row spacings, perpendicular to red fescue rows. Red fescue was also established without a companion crop as a control. Companion crop tiller height, tillers m⁻² and leaf area tiller⁻¹ were measured to determine their influence on red fescue growth and development during establishment. The effect of cereal companion crops on red fescue environment was investigated by measuring photosynthetic photon flux density (PPFD) incident on red fescue plants and by determining soil moisture levels. Red fescue tiller height, leaf area, dry matter production, and tillers m⁻² were examined to evaluate the effect of companion crops on red fescue growth. Companion crop grain yields were obtained to calculate additional revenues from establishment with companion crops. First-year red fescue seed yield and yield components were measured to determine the seed production capability of red fescue established with cereal companion crops. Finally, a partial budgeting technique was employed to evaluate the economic feasibility of companion cropping in Oregon. Cereal companion crops markedly reduced PPFD incident on red fescue plants. This greatly decreased red fescue tiller m⁻², dry matter m⁻², individual tiller weight, and increased the height of tillers. Leaf area tiller⁻¹ was generally unaffected by companion crops. Increasing companion crop row spacing resulted in more red fescue tillers m⁻², dry matter m⁻² and reduced etiolation of tillers because of higher PPFD availability. Soil moisture content was not decreased by establishment with cereal companion crops. Although companion crops adversely affected red fescue growth during the establishment year, first-year seed yield was not significantly reduced. Red fescue seed yields ranged from 490 kg ha⁻¹ when planted with Hill 81 wheat to 654 kg ha⁻¹ with Scio barley. The seed yield of red fescue planted without a companion crop was 589 kg ha⁻¹. Establishment with Yamhill wheat in 15-cm rows increased net income over a two-year period by $416 ha⁻¹ over monocultural red fescue. Establishment with Hesk barley proved to be the least successful in terms of income. Establishment with companion crops was shown to be most profitable when cereal market prices were high and red fescue prices low. The results of this research clearly indicate the potential for increased profits by establishment of red fescue seed crops with cereal companion crops. Title: Effect of cereal companion crops on the establishment of red fescue (Festuca rubra L.) for seed production Author: Chastain, Thomas G. Some perennial grass seed crops such as red fescue (Festuca rubra L.) do not produce a profitable seed crop during the first growing season. The present establishment method in Oregon for red fescue seed crops generally entails spring planting which does not satisfy vernalization requirements for seed production in the year of planting. This establishment procedure relies on the amortization of establishment costs over the seed producing life of the stand. In Europe, perennial grass seed crops are often established with annual companion crops such as winter rape, flax, peas and cereals. Companion crops provide income in the year of establishment, thereby increasing the profitability of the seed production venture over the life of the stand. However, the companion crop competes with the grass seed crop for light, soil moisture and nutrients which often causes unsatisfactory establishment. The primary objective of this study was to determine the feasibility of establishing red fescue with cereal companion crops in Oregon's Willamette Valley. The second objective was to examine the influence of cereal companion crops, cultivars and row spacings on the growth and environment of red fescue. This was investigated to identify companion cropping methods that would be the least competitive with the establishing seed crop. The third objective was to evaluate the effect of companion cropping on subsequent red fescue seed production and income relationships over a two-year period. Two experiments were initiated in October 1982 and October 1983 at the Oregon State University Hyslop Crop Science Field Laboratory. 'Pennlawn' red fescue was established with two winter wheat cultivars, 'Hill 81' and 'Yamhill1, and two winter barley cultivars, 'Hesk' and 'Scio', as companion crops. Cereal companion crops were drilled in 15-, 30-, 45-, and 60-cm row spacings, perpendicular to red fescue rows. Red fescue was also established without a companion crop as a control. Companion crop tiller height, tillers m⁻² and leaf area tiller⁻¹ were measured to determine their influence on red fescue growth and development during establishment. The effect of cereal companion crops on red fescue environment was investigated by measuring photosynthetic photon flux density (PPFD) incident on red fescue plants and by determining soil moisture levels. Red fescue tiller height, leaf area, dry matter production, and tillers m⁻² were examined to evaluate the effect of companion crops on red fescue growth. Companion crop grain yields were obtained to calculate additional revenues from establishment with companion crops. First-year red fescue seed yield and yield components were measured to determine the seed production capability of red fescue established with cereal companion crops. Finally, a partial budgeting technique was employed to evaluate the economic feasibility of companion cropping in Oregon. Cereal companion crops markedly reduced PPFD incident on red fescue plants. This greatly decreased red fescue tiller m⁻², dry matter m⁻², individual tiller weight, and increased the height of tillers. Leaf area tiller⁻¹ was generally unaffected by companion crops. Increasing companion crop row spacing resulted in more red fescue tillers m⁻², dry matter m⁻² and reduced etiolation of tillers because of higher PPFD availability. Soil moisture content was not decreased by establishment with cereal companion crops. Although companion crops adversely affected red fescue growth during the establishment year, first-year seed yield was not significantly reduced. Red fescue seed yields ranged from 490 kg ha⁻¹ when planted with Hill 81 wheat to 654 kg ha⁻¹ with Scio barley. The seed yield of red fescue planted without a companion crop was 589 kg ha⁻¹. Establishment with Yamhill wheat in 15-cm rows increased net income over a two-year period by $416 ha⁻¹ over monocultural red fescue. Establishment with Hesk barley proved to be the least successful in terms of income. Establishment with companion crops was shown to be most profitable when cereal market prices were high and red fescue prices low. The results of this research clearly indicate the potential for increased profits by establishment of red fescue seed crops with cereal companion crops. Close

• 34. [Article] Biological considerations for a new approach to regulating genetically modified crops in the United States

  The debate over GM crops is one of the most controversial issues of recent decades. The debate has many dimensions, including environmental impacts, benefits and risks to human health, intellectual property ...

  Citation × Citation Citation Abstract Copy Title: Biological considerations for a new approach to regulating genetically modified crops in the United States Author: McDonough, Ashley The debate over GM crops is one of the most controversial issues of recent decades. The debate has many dimensions, including environmental impacts, benefits and risks to human health, intellectual property rights, adequacy of biosafety regulations, and fundamental ethical acceptability. The potential benefits of GM crops are numerous, including improved nutritional value, decreased production costs, resistance to pests, and reduced pesticide use. However, there are also substantial and complex health, environmental, and social risks, including effects on gene flow and biodiversity, creation of new toxins or allergens in food, consolidation of seed companies, and restricted access to genetic information and methods. Current US regulations are imposed only on crops produced through recombinant DNA methods, though all of these risks apply to crops modified through conventional biotechnologies as well. I argue that this current regulatory system impedes progress by presenting large obstacles to even low risk GM crops with medical and economic benefits. I suggest that a better approach would be a tiered system that takes into account the specific biological properties of the modified traits, the biology of the crops in which they are produced, and the environments in which they are grown. Title: Biological considerations for a new approach to regulating genetically modified crops in the United States Author: McDonough, Ashley The debate over GM crops is one of the most controversial issues of recent decades. The debate has many dimensions, including environmental impacts, benefits and risks to human health, intellectual property rights, adequacy of biosafety regulations, and fundamental ethical acceptability. The potential benefits of GM crops are numerous, including improved nutritional value, decreased production costs, resistance to pests, and reduced pesticide use. However, there are also substantial and complex health, environmental, and social risks, including effects on gene flow and biodiversity, creation of new toxins or allergens in food, consolidation of seed companies, and restricted access to genetic information and methods. Current US regulations are imposed only on crops produced through recombinant DNA methods, though all of these risks apply to crops modified through conventional biotechnologies as well. I argue that this current regulatory system impedes progress by presenting large obstacles to even low risk GM crops with medical and economic benefits. I suggest that a better approach would be a tiered system that takes into account the specific biological properties of the modified traits, the biology of the crops in which they are produced, and the environments in which they are grown. Close

• 35. [Article] The effect of soil acidity and lime placement on root growth and yield of winter wheat and alfalfa

  The application of lime to an acid Nekia soil significantly increased the yield of winter wheat and alfalfa in a field experiment. Crop yields maximized when the lime was partially mixed into the surface four ...

  Citation × Citation Citation Abstract Copy Title: The effect of soil acidity and lime placement on root growth and yield of winter wheat and alfalfa Author: Kauffman, Marvin Dean The application of lime to an acid Nekia soil significantly increased the yield of winter wheat and alfalfa in a field experiment. Crop yields maximized when the lime was partially mixed into the surface four inches of the soil. Thorough mixing of the lime into the surface six inches of soil did not increase crop yields over partial mixing of lime, and on some plots the yields were reduced by the more thorough mixing treatment. The reduction in yield on the thoroughly mixed plots occurred with the lower rates of lime application. Deterioration of soil structure due to rototilling was also a factor in the reduction of yield in the plots where the lime was thoroughly mixed. The yields of wheat decreased over a three-year period following the application of one ton of lime per acre. It was felt that part of this decrease in yield was caused by a more thorough mixing of the lime into the soil with annual seedbed preparation on the partially mixed plots, and by a decrease of Ca and increase of Al in the soil solution as the quantity of free lime in the soil decreased. The importance of the soil solution pH and Al and Ca concentrations in the soil solution is also demonstrated by the fact that the R 2 values for the relationship between the soil test pH and wheat yields, were highest for the 1 N KC1 pH values the first two years, and highest for the water pH value the third year. Third-year wheat yields were also decreased by an infestation of the root fungus, Ophiobolus Graninus, with the adverse effect on the yield decreasing as the lime rates increased. High levels of soil acidity adversely affected the survival of the alfalfa seedlings and the rhizobia which inoculate the alfalfa. The concentration of nitrogen in the plants and the quantity of nitrogen harvested in the plants, increased as the rate of lime applied increased. The wheat and alfalfa roots which grew in the unlimed soil exhibited Al-toxicity symptoms. The Al-toxic roots were thicker than the healthy roots, and there was very little lateral root development on the Al-affected roots. The application of the intermediate and high rates of lime to the acid Nekia soil eliminated the Al-toxicity symptoms and promoted the growth of fine fibrous root systems. The distribution of the alfalfa roots in the samples taken from the field experiment, corresponded with the distribution of the lime in the soil. The field experimental data showed that the yields of wheat and alfalfa were closely correlated to the weight of the root samples. Growth chamber experiments using winter wheat as an indicator crop and acid Nekia and Dayton soils were also conducted. Maximum yields of dry matter were harvested when 30 per cent of the total soil volume was limed, and the dry matter yield decreased as the low rate of lime was mixed into larger volumes of soil. The wheat roots grew in the limed portion of soil, whereas root growth was restricted in the unlimed soil. Plant analysis data showed that the concentrations of plant nutrients were similar for all lime treatments. Plant water potential data indicated that water stress induced by Al-toxicity of wheat roots contributed to the lower yields of wheat grown in soil receiving zero and one ton of lime per acre. Title: The effect of soil acidity and lime placement on root growth and yield of winter wheat and alfalfa Author: Kauffman, Marvin Dean The application of lime to an acid Nekia soil significantly increased the yield of winter wheat and alfalfa in a field experiment. Crop yields maximized when the lime was partially mixed into the surface four inches of the soil. Thorough mixing of the lime into the surface six inches of soil did not increase crop yields over partial mixing of lime, and on some plots the yields were reduced by the more thorough mixing treatment. The reduction in yield on the thoroughly mixed plots occurred with the lower rates of lime application. Deterioration of soil structure due to rototilling was also a factor in the reduction of yield in the plots where the lime was thoroughly mixed. The yields of wheat decreased over a three-year period following the application of one ton of lime per acre. It was felt that part of this decrease in yield was caused by a more thorough mixing of the lime into the soil with annual seedbed preparation on the partially mixed plots, and by a decrease of Ca and increase of Al in the soil solution as the quantity of free lime in the soil decreased. The importance of the soil solution pH and Al and Ca concentrations in the soil solution is also demonstrated by the fact that the R 2 values for the relationship between the soil test pH and wheat yields, were highest for the 1 N KC1 pH values the first two years, and highest for the water pH value the third year. Third-year wheat yields were also decreased by an infestation of the root fungus, Ophiobolus Graninus, with the adverse effect on the yield decreasing as the lime rates increased. High levels of soil acidity adversely affected the survival of the alfalfa seedlings and the rhizobia which inoculate the alfalfa. The concentration of nitrogen in the plants and the quantity of nitrogen harvested in the plants, increased as the rate of lime applied increased. The wheat and alfalfa roots which grew in the unlimed soil exhibited Al-toxicity symptoms. The Al-toxic roots were thicker than the healthy roots, and there was very little lateral root development on the Al-affected roots. The application of the intermediate and high rates of lime to the acid Nekia soil eliminated the Al-toxicity symptoms and promoted the growth of fine fibrous root systems. The distribution of the alfalfa roots in the samples taken from the field experiment, corresponded with the distribution of the lime in the soil. The field experimental data showed that the yields of wheat and alfalfa were closely correlated to the weight of the root samples. Growth chamber experiments using winter wheat as an indicator crop and acid Nekia and Dayton soils were also conducted. Maximum yields of dry matter were harvested when 30 per cent of the total soil volume was limed, and the dry matter yield decreased as the low rate of lime was mixed into larger volumes of soil. The wheat roots grew in the limed portion of soil, whereas root growth was restricted in the unlimed soil. Plant analysis data showed that the concentrations of plant nutrients were similar for all lime treatments. Plant water potential data indicated that water stress induced by Al-toxicity of wheat roots contributed to the lower yields of wheat grown in soil receiving zero and one ton of lime per acre. Close

• 36. [Article] Chilling as a factor in crop location with particular reference to deciduous orchards in California

  Several empirical formulas that may be used to estimate available chilling are presented in this study. Many climatic parameters were considered in the derivation of these formulas. One equation employing ...

  Citation × Citation Citation Abstract Copy Title: Chilling as a factor in crop location with particular reference to deciduous orchards in California Author: Aron, Robert Henry Several empirical formulas that may be used to estimate available chilling are presented in this study. Many climatic parameters were considered in the derivation of these formulas. One equation employing only maximum and minimum temperatures had a coefficients of correlation (R) and R² values of .978 and .957, respectively. This equation was used in estimating the availability of chilling at 273 stations throughout California. Using these estimates and considering such factors as altitude and marine influences, the availability of chilling throughout California was mapped. Factors that influence the effectiveness of the chilling received such as low and high temperatures, high light intensity, shade, fog, cloud cover, topography and wind were analyzed. Which temperatures are most effective in satisfying the plant's chilling requirement, the amount required by different varieties, the effects and consequences of inadequate chilling, and treatments which may ameliorate the effects of inadequate chilling were considered. Hormonal and physical and anatomical plant response changes occurring during rest were discussed. Title: Chilling as a factor in crop location with particular reference to deciduous orchards in California Author: Aron, Robert Henry Several empirical formulas that may be used to estimate available chilling are presented in this study. Many climatic parameters were considered in the derivation of these formulas. One equation employing only maximum and minimum temperatures had a coefficients of correlation (R) and R² values of .978 and .957, respectively. This equation was used in estimating the availability of chilling at 273 stations throughout California. Using these estimates and considering such factors as altitude and marine influences, the availability of chilling throughout California was mapped. Factors that influence the effectiveness of the chilling received such as low and high temperatures, high light intensity, shade, fog, cloud cover, topography and wind were analyzed. Which temperatures are most effective in satisfying the plant's chilling requirement, the amount required by different varieties, the effects and consequences of inadequate chilling, and treatments which may ameliorate the effects of inadequate chilling were considered. Hormonal and physical and anatomical plant response changes occurring during rest were discussed. Close

• 37. [Article] Foliar interception and uptake of ³⁶Cl by crops

  Greenhouse studies were conducted to determine interception, absorption, and translocation values for foliar applied ³⁶Cl. Foliar interception and uptake of contaminated irrigation water by crops is a ...

  Citation × Citation Citation Abstract Copy Title: Foliar interception and uptake of ³⁶Cl by crops Author: Bytwerk, David Paul Greenhouse studies were conducted to determine interception, absorption, and translocation values for foliar applied ³⁶Cl. Foliar interception and uptake of contaminated irrigation water by crops is a major pathway for the transport of radionuclides to human beings in scenarios relevant to the waste disposal community. Performance assessments of many repositories that predict doses to people from long- term geological disposal of radioactive waste are equipped to consider foliar interception and uptake by crops on an element and crop specific basis in their predictions, but crop and element specific data does not exist in the literature to justify the choice of parameter values in these models. ³⁶Cl is among the isotopes for which there is a lack of data and has recently been predicted to be among the largest contributors to dose at the time of peak dose from many repositories. Reported here are ³⁶Cl foliar interception, absorption, and translocation parameters for three crops: a root vegetable -radishes, a fruit - beans, and a grain - wheat. Title: Foliar interception and uptake of ³⁶Cl by crops Author: Bytwerk, David Paul Greenhouse studies were conducted to determine interception, absorption, and translocation values for foliar applied ³⁶Cl. Foliar interception and uptake of contaminated irrigation water by crops is a major pathway for the transport of radionuclides to human beings in scenarios relevant to the waste disposal community. Performance assessments of many repositories that predict doses to people from long- term geological disposal of radioactive waste are equipped to consider foliar interception and uptake by crops on an element and crop specific basis in their predictions, but crop and element specific data does not exist in the literature to justify the choice of parameter values in these models. ³⁶Cl is among the isotopes for which there is a lack of data and has recently been predicted to be among the largest contributors to dose at the time of peak dose from many repositories. Reported here are ³⁶Cl foliar interception, absorption, and translocation parameters for three crops: a root vegetable -radishes, a fruit - beans, and a grain - wheat. Close

• 38. [Article] Improving nitrogen management with cover crops in organic broccoli production

  Legume cover crops can serve as important sources of nitrogen (N) in sustainable agriculture and can be economically beneficial when fertilizer inputs are reduced without a yield reduction. Synchronizing ...

  Citation × Citation Citation Abstract Copy Title: Improving nitrogen management with cover crops in organic broccoli production Author: Garrett, Amy (Amy Michelle) Legume cover crops can serve as important sources of nitrogen (N) in sustainable agriculture and can be economically beneficial when fertilizer inputs are reduced without a yield reduction. Synchronizing N mineralization from organic materials with the needs of the subsequent crop is a challenge for organic growers. Predicting plant available nitrogen from cover crop residue enables N fertilizer inputs to be adjusted for optimum economic yield and reduced environmental risk. An experiment was conducted near Corvallis, OR in 2006 through 2008 to evaluate cover crop and N effects in organic broccoli production in western Oregon. The specific objectives of this experiment were to: 1) evaluate biomass production and N accumulation from selected cover crop treatments; 2) compare the effects of selected cover crops grown as sole crops and as mixtures on broccoli yield, yield components, and net economic benefit; 3) estimate the quantity of feather meal N replaced by cover crops 4) estimate plant available nitrogen from cover crop residue in an organic broccoli production system; 5) evaluate soil NO₃₋N and petiole NO₃₋N as predictors of broccoli yield; and 6) evaluate models derived from laboratory incubation of cover crop residue to predict apparent nitrogen recovery (ANR) from cover crop residue in the field. The cover crop treatments included common vetch (Vicia sativa), phacelia (Phacelia tanacetifolia), 'Monida' oats (Avena sativa L.), phacelia plus common vetch, and 'Monida' oats plus common vetch. A fallow treatment was used as the control. Prior to incorporation, cover crop samples were collected from each block and frozen for later use in laboratory aerobic incubations. After the cover crops were flail-mowed and incorporated, four N rates (0, 100, 200, and 300 kg N ha⁻¹) were randomized within each cover crop treatment in a split plot design. All cover crop treatments produced much less biomass and accumulated less N in 2008 than in 2007. Planting vetch with oats or phacelia increased biomass production and N accumulation compared to sole crops in 2007 but not in 2008. Common vetch as a sole crop or in a mixture increased broccoli yield with 0 and 100 kg N ha⁻¹ applied compared to fallow. Legume cover crop mixtures with 100 kg N ha⁻¹ produced similar net economic returns for organic compared to fallow treatments with 300 kg N ha⁻¹. Nitrogen fertilizer input can be reduced by at least 100 kg N ha⁻¹ if common vetch is in the mixture and produces more than 5000 kg ha⁻¹ of biomass (130-180 kg N ha⁻¹). Vetch as a sole crop produced higher levels of soil NO₃₋N than the fallow treatments up to 80 days after soil incorporation in 2007. Oats and phacelia as sole crops, however, reduced soil NO₃₋N compared to fallow for up to 68 days after incorporation. Vetch mixtures with oats or phacelia produced intermediate levels of soil NO₃₋N between vetch as a sole crop and the fallow. Treatment effects were similar in 2008, but differences were less due to reduced cover crop biomass compared to 2007. Broccoli petiole nitrate levels were not affected by cover crop treatment in 2007, and there was no correlation with yield. In 2008, the oat cover crop treatment reduced broccoli petiole nitrate levels compared to the fallow. Petiole nitrate levels were strongly correlated with broccoli yield, with highest yields associated with petiole NO₃₋ N greater than 10,000 ppm. In the aerobic incubations with cover crop mixtures, a quadratic model described the relationship of percent N in the mixture to the apparent nitrogen recovery (ANR) at both 4 and 10 weeks. The highest ANR (about 40 percent) was similar for both extraction days. Net mineralization occurred when the percent N of the cover crop mixture was 1.5-1.8 percent. There was a strong correlation in 2007 between the ANR predicted by the incubation-derived model and the ANR in the soil and in the aboveground broccoli biomass. The model over predicted the ANR in the field soil, however the model more accurately predicted ANR in the broccoli biomass. The incubation model correctly predicted negative ANR values for the oat and phacelia cover-crop treatments. In 2008, the laboratory-predicted ANR and the field soil ANR were correlated (r²=.45), and the laboratory model over predicted the field ANR. The incubation model gave a poor prediction of broccoli biomass ANR. Title: Improving nitrogen management with cover crops in organic broccoli production Author: Garrett, Amy (Amy Michelle) Legume cover crops can serve as important sources of nitrogen (N) in sustainable agriculture and can be economically beneficial when fertilizer inputs are reduced without a yield reduction. Synchronizing N mineralization from organic materials with the needs of the subsequent crop is a challenge for organic growers. Predicting plant available nitrogen from cover crop residue enables N fertilizer inputs to be adjusted for optimum economic yield and reduced environmental risk. An experiment was conducted near Corvallis, OR in 2006 through 2008 to evaluate cover crop and N effects in organic broccoli production in western Oregon. The specific objectives of this experiment were to: 1) evaluate biomass production and N accumulation from selected cover crop treatments; 2) compare the effects of selected cover crops grown as sole crops and as mixtures on broccoli yield, yield components, and net economic benefit; 3) estimate the quantity of feather meal N replaced by cover crops 4) estimate plant available nitrogen from cover crop residue in an organic broccoli production system; 5) evaluate soil NO₃₋N and petiole NO₃₋N as predictors of broccoli yield; and 6) evaluate models derived from laboratory incubation of cover crop residue to predict apparent nitrogen recovery (ANR) from cover crop residue in the field. The cover crop treatments included common vetch (Vicia sativa), phacelia (Phacelia tanacetifolia), 'Monida' oats (Avena sativa L.), phacelia plus common vetch, and 'Monida' oats plus common vetch. A fallow treatment was used as the control. Prior to incorporation, cover crop samples were collected from each block and frozen for later use in laboratory aerobic incubations. After the cover crops were flail-mowed and incorporated, four N rates (0, 100, 200, and 300 kg N ha⁻¹) were randomized within each cover crop treatment in a split plot design. All cover crop treatments produced much less biomass and accumulated less N in 2008 than in 2007. Planting vetch with oats or phacelia increased biomass production and N accumulation compared to sole crops in 2007 but not in 2008. Common vetch as a sole crop or in a mixture increased broccoli yield with 0 and 100 kg N ha⁻¹ applied compared to fallow. Legume cover crop mixtures with 100 kg N ha⁻¹ produced similar net economic returns for organic compared to fallow treatments with 300 kg N ha⁻¹. Nitrogen fertilizer input can be reduced by at least 100 kg N ha⁻¹ if common vetch is in the mixture and produces more than 5000 kg ha⁻¹ of biomass (130-180 kg N ha⁻¹). Vetch as a sole crop produced higher levels of soil NO₃₋N than the fallow treatments up to 80 days after soil incorporation in 2007. Oats and phacelia as sole crops, however, reduced soil NO₃₋N compared to fallow for up to 68 days after incorporation. Vetch mixtures with oats or phacelia produced intermediate levels of soil NO₃₋N between vetch as a sole crop and the fallow. Treatment effects were similar in 2008, but differences were less due to reduced cover crop biomass compared to 2007. Broccoli petiole nitrate levels were not affected by cover crop treatment in 2007, and there was no correlation with yield. In 2008, the oat cover crop treatment reduced broccoli petiole nitrate levels compared to the fallow. Petiole nitrate levels were strongly correlated with broccoli yield, with highest yields associated with petiole NO₃₋ N greater than 10,000 ppm. In the aerobic incubations with cover crop mixtures, a quadratic model described the relationship of percent N in the mixture to the apparent nitrogen recovery (ANR) at both 4 and 10 weeks. The highest ANR (about 40 percent) was similar for both extraction days. Net mineralization occurred when the percent N of the cover crop mixture was 1.5-1.8 percent. There was a strong correlation in 2007 between the ANR predicted by the incubation-derived model and the ANR in the soil and in the aboveground broccoli biomass. The model over predicted the ANR in the field soil, however the model more accurately predicted ANR in the broccoli biomass. The incubation model correctly predicted negative ANR values for the oat and phacelia cover-crop treatments. In 2008, the laboratory-predicted ANR and the field soil ANR were correlated (r²=.45), and the laboratory model over predicted the field ANR. The incubation model gave a poor prediction of broccoli biomass ANR. Close

• 39. [Article] A production function analysis of water resource productivity in Pacific Northwest agriculture

  The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This ...

  Citation × Citation Citation Abstract Copy Title: A production function analysis of water resource productivity in Pacific Northwest agriculture Author: Holloway, Milton L. The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This rivalry and the long run prospects for water shortages have increased the demand for research concerning the productivity of this resource in alternative uses. This demand exists because the distribution and use of water resources require investment which typically comes from both public and private sources. Private and public planning groups seek answers to questions regarding future water resource development alternatives. Agriculture has historically been a major user of water in the Pacific Northwest. A substantial portion of total investment in water resource development has also been, in agriculture. As a result water use planners and decision making bodies are necessarily interested in water use in agriculture. The success of water resource planning requires answers to questions regarding the value of the productivity of water in all its major uses, including various aspects of water use in agriculture. Different aspects of water use in agriculture which are important to decision makers include (1) the value productivity of various kinds or types of water resource investments, (2) the value productivity of water in various kinds of agricultural production in different geographical areas, and (3) the returns to private and public investment in agricultural water resources. This study was directed to providing answers to these questions. Pacific Northwest agriculture was studied from this viewpoint. Agricultural water resources were classified as irrigation, drainage, and water related Agricultural Conservation Program (ACP) practices. These are the major classifications of water resources in which investments are made in the Pacific Northwest. Production function analysis was selected as a method of investigation. Production functions were estimated for five areas or subregions in the Pacific Northwest. These areas are composed of counties with similar patterns of production. The Agricultural Census was the primary data surce, supplemented by related U.S. Department of Agriculture publications, and various state publications, Ordinary least-squares regression (OLS) techniques were employed to derive the initial estimates of the parameters of the production function models. Tests for detecting interdependence within the independent variable set of the models revealed a considerable degree of instability in the OLS parameter estimates. This condition makes the OLS solutions (and various derivations) particularly vulnerable to change from measurement error, poor model specification, and equation form. A prior information model was selected to explicitly include available prior knowledge in the estimation process. The model selected allows (1) tests of comparability of the two information sources (prior and sample), (2) over-all contribution of prior information to the new solution set, and (3) derivation of percentage contribution of the two information sources to individual parameter estimates. The results of the study indicate that no reliable estimates of value of production from drainage and ACP were possible from the sample information. Returns to irrigation were considered lower than expected in two of the farming areas and higher than expected in another. Estimated returns were high in the area which produces primarily field crops (about nine dollars per acre foot). The area has a small level of current irrigation development. Indications are that irrigation development is probably beyond the optimum level in the area where most large, projects have been developed in the past (less than four dollars per acre foot). Future development would be most profitable (assuming equal development cost) in the dryland field crop area. Estimated returns to other factor inputs indicate (1) low returns to labor in two areas, (2) generally high returns to current operating expenditures, and (3) low returns to machinery capital. Returns to cropland were about as expected in two areas (five to seven percent) but low in two other areas (about two percent). Indications are that labor mobility should be increased in the area and that future land development should be in the livestock-field crop and the field crop areas rather than the coastal area or the west-central valley areas (primarily the Willamette Valley). Title: A production function analysis of water resource productivity in Pacific Northwest agriculture Author: Holloway, Milton L. The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This rivalry and the long run prospects for water shortages have increased the demand for research concerning the productivity of this resource in alternative uses. This demand exists because the distribution and use of water resources require investment which typically comes from both public and private sources. Private and public planning groups seek answers to questions regarding future water resource development alternatives. Agriculture has historically been a major user of water in the Pacific Northwest. A substantial portion of total investment in water resource development has also been, in agriculture. As a result water use planners and decision making bodies are necessarily interested in water use in agriculture. The success of water resource planning requires answers to questions regarding the value of the productivity of water in all its major uses, including various aspects of water use in agriculture. Different aspects of water use in agriculture which are important to decision makers include (1) the value productivity of various kinds or types of water resource investments, (2) the value productivity of water in various kinds of agricultural production in different geographical areas, and (3) the returns to private and public investment in agricultural water resources. This study was directed to providing answers to these questions. Pacific Northwest agriculture was studied from this viewpoint. Agricultural water resources were classified as irrigation, drainage, and water related Agricultural Conservation Program (ACP) practices. These are the major classifications of water resources in which investments are made in the Pacific Northwest. Production function analysis was selected as a method of investigation. Production functions were estimated for five areas or subregions in the Pacific Northwest. These areas are composed of counties with similar patterns of production. The Agricultural Census was the primary data surce, supplemented by related U.S. Department of Agriculture publications, and various state publications, Ordinary least-squares regression (OLS) techniques were employed to derive the initial estimates of the parameters of the production function models. Tests for detecting interdependence within the independent variable set of the models revealed a considerable degree of instability in the OLS parameter estimates. This condition makes the OLS solutions (and various derivations) particularly vulnerable to change from measurement error, poor model specification, and equation form. A prior information model was selected to explicitly include available prior knowledge in the estimation process. The model selected allows (1) tests of comparability of the two information sources (prior and sample), (2) over-all contribution of prior information to the new solution set, and (3) derivation of percentage contribution of the two information sources to individual parameter estimates. The results of the study indicate that no reliable estimates of value of production from drainage and ACP were possible from the sample information. Returns to irrigation were considered lower than expected in two of the farming areas and higher than expected in another. Estimated returns were high in the area which produces primarily field crops (about nine dollars per acre foot). The area has a small level of current irrigation development. Indications are that irrigation development is probably beyond the optimum level in the area where most large, projects have been developed in the past (less than four dollars per acre foot). Future development would be most profitable (assuming equal development cost) in the dryland field crop area. Estimated returns to other factor inputs indicate (1) low returns to labor in two areas, (2) generally high returns to current operating expenditures, and (3) low returns to machinery capital. Returns to cropland were about as expected in two areas (five to seven percent) but low in two other areas (about two percent). Indications are that labor mobility should be increased in the area and that future land development should be in the livestock-field crop and the field crop areas rather than the coastal area or the west-central valley areas (primarily the Willamette Valley). Close

• 40. [Article] A production function analysis of water resource productivity in Pacific Northwest agriculture

  The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This ...

  Citation × Citation Citation Abstract Copy Title: A production function analysis of water resource productivity in Pacific Northwest agriculture Author: Holloway, Milton L. The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This rivalry and the long run prospects for water shortages have increased the demand for research concerning the productivity of this resource in alternative uses. This demand exists because the distribution and use of water resources require investment which typically comes from both public and private sources. Private and public planning groups seek answers to questions regarding future water resource development alternatives. Agriculture has historically been a major user of water in the Pacific Northwest. A substantial portion of total investment in water resource development has also been in agriculture. As a result water use planners and decision making bodies are necessarily interested in water use in agriculture. The success of water resource planning requires answers to questions regarding the value of the productivity of water in all its major uses, including various aspects of water use in agriculture. Different aspects of water use in agriculture which are important to decision makers include (1) the value productivity of various kinds or types of water resource investments, (2) the value productivity of water in various kinds of agricultural production in different geographical areas, and (3) the returns to private and public investment in agricultural water resources. This study was directed to providing answers to these questions. Pacific Northwest agriculture was studied from this viewpoint. Agricultural water resources were classified as irrigation, drainage, and water related Agricultural Conservation Program (ACP) practices. These are the major classifications of water resources in which investments are made in the Pacific Northwest. Production function analysis was selected as a method of investigation. Production functions were estimated for five areas or subregions in the Pacific Northwest. These areas are composed of counties with similar patterns of production. The Agricultural Census was the primary data source, supplemented by related. U. S. Department of Agriculture publications, and various state publications. Ordinary least-squares regression (OLS) techniques were employed to derive the initial estimates of the parameters of the production function models. Tests for detecting interdependence within the independent variable set of the models revealed a considerable degree of instability in the OLS parameter estimates. This condition makes the OLS solutions (and various derivations) particularly vulnerable to change from measurement error, poor model specification, and equation form. A prior information model was selected to explicitly include available prior knowledge in the estimation process. The model selected allows (1) tests of comparability of the two information sources (prior and sample), (2) over-all contribution of prior information to the new solution set, and (3) derivation of percentage contribution of the two information sources to individual parameter estimates. The results of the study indicate that no reliable estimates of value of production from drainage and ACP were possible from the sample information. Returns to irrigation were considered lower than expected in two of the farming areas and higher than expected in another. Estimated returns were high in the area which produces primarily field crops (about nine dollars per acre foot). The area has a small level of current irrigation development. Indications are that irrigation development is probably beyond the optimum level in the area where most large projects have been developed in the past (less than four dollars per acre foot). Future development would be most profitable (assuming equal development cost) in the dryland field crop area. Estimated returns to other factor inputs indicate (1) low returns to labor in two areas, (2) generally high returns to current operating expenditures, and (3) low returns to machinery capital. Returns to cropland were about as expected in two areas (five to seven percent) but low in two other areas (about two percent). Indications are that labor mobility should be increased in the area and that future land development should be in the livestock-field crop and the field crop areas rather than the coastal area or the west-central valley areas (primarily the Willamette Valley). Title: A production function analysis of water resource productivity in Pacific Northwest agriculture Author: Holloway, Milton L. The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This rivalry and the long run prospects for water shortages have increased the demand for research concerning the productivity of this resource in alternative uses. This demand exists because the distribution and use of water resources require investment which typically comes from both public and private sources. Private and public planning groups seek answers to questions regarding future water resource development alternatives. Agriculture has historically been a major user of water in the Pacific Northwest. A substantial portion of total investment in water resource development has also been in agriculture. As a result water use planners and decision making bodies are necessarily interested in water use in agriculture. The success of water resource planning requires answers to questions regarding the value of the productivity of water in all its major uses, including various aspects of water use in agriculture. Different aspects of water use in agriculture which are important to decision makers include (1) the value productivity of various kinds or types of water resource investments, (2) the value productivity of water in various kinds of agricultural production in different geographical areas, and (3) the returns to private and public investment in agricultural water resources. This study was directed to providing answers to these questions. Pacific Northwest agriculture was studied from this viewpoint. Agricultural water resources were classified as irrigation, drainage, and water related Agricultural Conservation Program (ACP) practices. These are the major classifications of water resources in which investments are made in the Pacific Northwest. Production function analysis was selected as a method of investigation. Production functions were estimated for five areas or subregions in the Pacific Northwest. These areas are composed of counties with similar patterns of production. The Agricultural Census was the primary data source, supplemented by related. U. S. Department of Agriculture publications, and various state publications. Ordinary least-squares regression (OLS) techniques were employed to derive the initial estimates of the parameters of the production function models. Tests for detecting interdependence within the independent variable set of the models revealed a considerable degree of instability in the OLS parameter estimates. This condition makes the OLS solutions (and various derivations) particularly vulnerable to change from measurement error, poor model specification, and equation form. A prior information model was selected to explicitly include available prior knowledge in the estimation process. The model selected allows (1) tests of comparability of the two information sources (prior and sample), (2) over-all contribution of prior information to the new solution set, and (3) derivation of percentage contribution of the two information sources to individual parameter estimates. The results of the study indicate that no reliable estimates of value of production from drainage and ACP were possible from the sample information. Returns to irrigation were considered lower than expected in two of the farming areas and higher than expected in another. Estimated returns were high in the area which produces primarily field crops (about nine dollars per acre foot). The area has a small level of current irrigation development. Indications are that irrigation development is probably beyond the optimum level in the area where most large projects have been developed in the past (less than four dollars per acre foot). Future development would be most profitable (assuming equal development cost) in the dryland field crop area. Estimated returns to other factor inputs indicate (1) low returns to labor in two areas, (2) generally high returns to current operating expenditures, and (3) low returns to machinery capital. Returns to cropland were about as expected in two areas (five to seven percent) but low in two other areas (about two percent). Indications are that labor mobility should be increased in the area and that future land development should be in the livestock-field crop and the field crop areas rather than the coastal area or the west-central valley areas (primarily the Willamette Valley). Close