Journal of the Science of Food and Agriculture, 2007
ABSTRACT As the name implies, a cover crop consists of plants grown primarily to keep the land co... more ABSTRACT As the name implies, a cover crop consists of plants grown primarily to keep the land covered, especially during the off-season or between cash crops. In temperate regions like most of Europe and North America, a cover crop sown immediately after the main crop harvest in fall is considered a winter cover crop. It will grow in the fall, either subjected to frost- kill or go into relative dormancy during the dead of winter, and then, if winter-hardy, recommence growth in very early spring before soils are warm and dry enough for the next cash crop. If the climate is sufficiently mild, such cover crops may produce substantial above-ground dry matter (3000-6000kg
Goals on agricultural sustainability have been articulated in the publication “Towards Sustainabl... more Goals on agricultural sustainability have been articulated in the publication “Towards Sustainable Agricultural Systems in the 21st Century” (National Research Council). These goals include: 1. Farms must be profitable. 2. Farms must enhance environmental quality. 3. Farms must increase the quality of life for farmers and society. 4. Farms must produce enough to satisfy human needs. University of Maryland research has indicated that management-intensive grazing (MIG) dairy farms may achieve these goals better than conventional confinement (CC) dairy farms. Financial data collected from dairy farms indicates that MIG farms were more profitable than CC farms on a per cow, per milk-weight, and per acre basis for farms with less than 200 cows (Hanson, et.al. 2013). Profits of MIG farms were also less variable, so that MIG farms faced less income risk. Grazing has other benefits as well. Grazing seems to be much healthier for dairy cows. Veterinary, breeding, and medicine costs are much ...
Intercropping orchards with cover crops is an important practice for achieving sustainable soil m... more Intercropping orchards with cover crops is an important practice for achieving sustainable soil management. However, little research has addressed the development of a soil quality index (SQI) to evaluate cover crop effects on orchard soil quality. The aim of this study was to ascertain whether cover cropping improves soil quality and fruit yield of Goji (Lycium barbarum L.) while reducing or replacing organic fertilizer application. The main treatments were the traditional management of L. barbarum as a monocrop (M) and intercropping Goji with radish (Raphanus sativus L.) as an annual cover crop (I). Within the main treatments, different levels of organic fertilizer were applied at 0 kg·plant−1 (M0), 2 kg·plant−1 (M1), and 4 kg·plant−1 (M2). After six years of planting, we analyzed the changes in soil quality caused by cover cropping with different organic fertilizer levels based on the SQI method. Goji yields were used for validation of the SQI derived from a minimum data set of s...
Student evaluation can be greatly facilitated by using computer scored and analyzed multiple choi... more Student evaluation can be greatly facilitated by using computer scored and analyzed multiple choice tests. Test parameters can aid the instructor in the interpretation of student scores, and item analyses can provide him with valuable feedback for improving both teaching and writing. The caliber of testing influences the caliber of learning, and at college level it is more appropriate to evaluate complex learning outcomes than it is simply to test recall of information. Therefore we are justified in making an effort to evaluate attainment of higher levels of knowledge on multiple choice tests and to de~mphasize rote memorization. This paper describes ways of increasing the quality and usefulness of computer scored tests by examples from an introductory soil science course, The authors use test and item analysis; define the variable to be tested; and make a table of specifications to assure that the test reflects a balance, characteristic of the course, of both subject matter and level of knowledge. Most of their examples show how to write better test items, but they also give examples of ways to reduce the guessing factor and how to increase the value of the distractor. Some techniques for writing test items for high-level knowledge are: 1) using terms in problems rather than defining the terms, 2) presenting novel rather than familiar situations , 3} using problems that require applying knowledge , and 4) asking for interpretations of data requiring both knowledge and reasoning. A. T MANY land-grant universities, enrollments in basic agricultural science courses have increased dramatically over the past few years. Classes have jumped in size from 20 or 30 students to "megalectures" of several hundred students. Teaching methods have had to undergo considerable modification in order to cope with fundamental changes in the classroom situation. The challenge is to maintain or improve the quality of instruction and validity of student evaluation in these large classes. Among the diverse approaches taken by agronomist educators, certain practices seem to have gained widespread acceptance. One evaluation tool is the use of computer-scored achievement tests. At best this type of testing can result in fast, fair, and accurate evaluation of student achievement and readily accessible feedback on the progress of of the teaching process. At worst it reduces testing and achievement to the level of rote recall of un-connected facts. This paper discusses ways of increasing the quality and usefulness of computer scored tests used in …
Though the use of fertilizers can enhance productivity and increase profits for small-scale farmi... more Though the use of fertilizers can enhance productivity and increase profits for small-scale farming families, two barriers to their adoption have proved critical. First, many farmers often cannot afford to buy fertilizers; second, use recommendations from government sources may not be appropriate for specific farms. In Tanzania, 1 our multi-disciplinary team used low-cost soil testing to pair field-specific recommendations with subsidy vouchers to help cover the cost of fertilizer purchase. Our results show that farmers benefitted significantly in both yields and profits when (1) fertilizer recommendations were calibrated to the needs of individual farms and (2) a subsidy made the recommended fertilizers affordable
Cover crops can reduce nitrate leaching after cash crop harvest. Despite widespread cover crop im... more Cover crops can reduce nitrate leaching after cash crop harvest. Despite widespread cover crop implementation there has been a limited impact on water quality in the Chesapeake Bay watershed. We hypothesize that typical timing for Maryland cover crop planting after cash crop harvest is too late to allow roots to take up substantial nitrate from the soil profile before it is leached by winter drainage water. Across four site-years (including sandy and silty soils) we compared various planting dates for a radish (Raphanus sativus, L)-crimson clover (Trifolium incarnatum, L.)-triticale (Triticosecale) cover crop mixture. Also, across two site-years we compared early-planted pure rye, radish, and a 3-species mixture to no cover. We measured cover crop biomass and N content and used tension lysimeters to measure deep soil porewater nitrate concentrations. Cumulative nitrate leaching was estimated from these concentrations and weather-based drainage estimates. Cover crops were planted on four dates over a six-week period. Overall, cover crops planted first, second, third, fourth, and no cover crop (just weeds) resulted in 3340, 3160, 1600, 303, and 164 kg ha-1 of biomass, biomass N accumulation of 65.5, 68.6, 44.0, 9.88, and 4.79 kg N ha-1 , and mean porewater concentrations of 2.71, 2.57, 4.72, 10.0, 17.1 mg L-1 of nitrate-N, respectively. Over two site-years, the three-species mix performed as well or better than pure rye or radish. Early planting altered cover crop species proportions, increased cover crop productivity and reduced nitrate leaching from agricultural fields. This article is protected by copyright. All rights reserved.
Forage radish (Raphanus sativus L. var. longipinnatus) is an increasingly popular winter cover cr... more Forage radish (Raphanus sativus L. var. longipinnatus) is an increasingly popular winter cover crop in the mid-Atlantic region of the United States. This crop can be used to scavenge residual soil nitrate (NO 3 −) and ammonium (NH 4 +), with the goal of reducing nitrogen (N) loss from agricultural fields and increasing N availability for subsequent crops. In the present work, two sites in Maryland were examined to investigate the influence of forage radish cover crop and residual N fertilizer from corn side-dressing on the forms and vertical distribution of soil N and the yield of subsequent no-till silage corn (Zea mays L.). Forage radish dry matter ranged from 1,965 to 3,360 kg ha −1 for shoots and 1,531.5 to 3,740 kg ha −1 for fleshy taproots. Forage radish had a marked influence on the distribution of NO 3 −-N in the soil profile; in the spring following a radish cover crop, NO 3 −-N was concentrated in the surface soil, with no accumulation in deep soil, even at the highest fertilization rate of 168 kg N ha −1. The cover crop had no significant influence on the NH 4 +-N or total N profile. The average silage corn yield was significantly improved following cover cropping. In addition, the yield increased with the highest N fertilization rate but was not affected by low or medium N fertilization rate. In conclusion, a radish cover crop captures large quantities of residual N from the deep soil following N side-dressing and can improve the yield of subsequent silage.
Green and animal manures provide plant-available N (PAN) in annual cropping systems and contribut... more Green and animal manures provide plant-available N (PAN) in annual cropping systems and contribute to improved soil quality. Our objectives were to determine the effects of cover crop residue type and pelletized poultry litter (PPL) application method on: (i) the spatiotemporal distribution of topsoil mineral N (N min), (ii) the average topsoil N min at four developmental stages of corn (Zea mays L.), and (iii) corn N uptake. we collected soil and plant samples from a factorial experiment that included three cover crop residues: hairy vetch (Vicia villosa Roth), cereal rye (Secale cereale L.), and a hairy vetch/cereal rye mixture; and four PPL treatments: no PPL and 3.5 Mg PPL ha-1 either broadcast at planting, subsurface banded at the fifthleaf stage, or broadcast and incorporated at planting. Most of the N min in the broadcast treatment was concentrated near the soil surface, N min associated with the subsurface band remained within 10 cm of the delivery location throughout the growing season, while N min was distributed to a depth of 20 cm in the incorporated treatment. Average N min to 30 cm was significantly greater in soil with hairy vetch residue than in soil with cereal rye residue at emergence and the fifth-leaf stage, while the cover crop mixture had average N min levels intermediate between the monocultures or similar to cereal rye depending on the year. In both years, corn N uptake tended to be greatest with hairy vetch residue and broadcast or subsurface band PPL application, averaging 215 kg ha-1 across years in these treatments.
Dairy farm size has increased in the United States, while the profit margin has decreased. An alt... more Dairy farm size has increased in the United States, while the profit margin has decreased. An alternative to confined feeding dairy farming is management intensive grazing (MIG), a grass-based system relying on rotational grazing for most of the herd’s dietary requirements. Previous research has measured high levels of nitrate leaching under MIG, citing the liquid nature and high nitrogen (N) content of urine. However, this research included heavy N fertilizer applications or was conducted on monolith lysimeters with artificial leaching processes and did not accurately represent mid-Atlantic MIG dairy farms. Phosphorus (P) losses have typically been attributed to runoff and erosion but are now being ascribed to leaching as well. To measure the magnitude of N and P losses to groundwater, we sampled shallow groundwater and pore water on one confined feeding and two MIG-based Maryland dairy farms between 2001 and 2004. Transects of nested piezometers and ceramic-tipped suction lysimete...
A study aimed at the assessment of the contribution of pigeon pea roots to N yield for the pigeon... more A study aimed at the assessment of the contribution of pigeon pea roots to N yield for the pigeon pea was conducted at Chitedze Agricultural Research Station (S 13 0 59' 23.2", E033 0 38' 36.8"), Malawi in the 2012/2013 cropping season. Ten treatments, replicated three times were laid in a randomized complete block design. Two pigeon pea varieties, long (ICEAP 04000) and medium duration (ICEAP 00557) and groundnut (CG 7) were grown as monocultures and intercrops. The intercrops involved planting either of the pigeon pea varieties with groundnut. Some of the plots were treated with triple super phosphate (TSP) at the rate of 25 kg P ha-1. Analysis of soil samples collected in all treatment plots indicate that the soil had low fertility, having; low organic carbon (1.4 %), low cation exchange capacity (CEC) (NH4OAc) (3.5-3.6 cmol (+) kg-1 soil) and low N (0.12%), while plant available phosphorus (Mehlich 3) was marginally adequate both in the top and sub soil (μ=21.5...
As the name implies, a cover crop consists of plants grown primarily to keep the land covered, es... more As the name implies, a cover crop consists of plants grown primarily to keep the land covered, especially during the off-season or between cash crops. In temperate regions like most of Europe and North America, a cover crop sown immediately after the main crop harvest in fall is considered a winter cover crop. It will grow in the fall, either subjected to frost-kill or go into relative dormancy during the dead of winter, and then, if winter-hardy, recommence growth in very early spring before soils are warm and dry enough for the next cash crop. If the climate is sufficiently mild, such cover crops may produce substantial above-ground dry matter (3000–6000kg ha−1) and nearly complete ground cover before being terminated. For many decades, the use of cover crops
Journal of the Science of Food and Agriculture, 2021
BACKGROUND Soybeans (Glycine max) are a major protein source for both humans and non-ruminant liv... more BACKGROUND Soybeans (Glycine max) are a major protein source for both humans and non-ruminant livestock, however, the usability of soybean protein is limited by the concentration of the essential sulfur (S) containing amino acids methionine and cysteine (MET+CYS). Traditional efforts to improve protein quality in soybeans have largely been focused on plant breeding, but soil S fertility may also influence seed MET+CYS concentration. Crop S deficiencies are increasingly common due to soil depletion by high yields and reduced atmospheric deposition. We report on a survey of commercial soybean fields and two replicated split-plot field experiments in the mid-Atlantic region, USA. The experimental treatments were two levels (0 or 100 kg S ha-1 ) of broadcast gypsum (CaSO4 ) and two levels (0 or 11 kg-S ha-1 ) of foliar Epsom Salt (MgSO4 ) applied to two soybean cultivars. The objective was to assess the variability of, and effect of S fertilization on S and MET+CYS concentrations in soybean seeds. RESULTS Sulfur ranged from 2.35 to 3.54 mg g-1 and MET+CYS ranged from 5.5 to 9.2 mg g-1 protein in seeds from commercial fields surveyed. Sulfur application increased seed MET+CYS concentration 1.3 to 2.0-fold in two replicated field experiments. Overall, MET+CYS concentration in protein ranged from 3.9 to 12.8 mg g-1 and was linearly predicted (R2 = 0.65) by seed S. CONCLUSIONS Soybean seed S and MET+CYS concentrations vary widely. We show that field-scale S application can greatly enhance soybean MET+CYS content and therefore protein quality. This article is protected by copyright. All rights reserved.
Journal of the Science of Food and Agriculture, 2007
ABSTRACT As the name implies, a cover crop consists of plants grown primarily to keep the land co... more ABSTRACT As the name implies, a cover crop consists of plants grown primarily to keep the land covered, especially during the off-season or between cash crops. In temperate regions like most of Europe and North America, a cover crop sown immediately after the main crop harvest in fall is considered a winter cover crop. It will grow in the fall, either subjected to frost- kill or go into relative dormancy during the dead of winter, and then, if winter-hardy, recommence growth in very early spring before soils are warm and dry enough for the next cash crop. If the climate is sufficiently mild, such cover crops may produce substantial above-ground dry matter (3000-6000kg
Goals on agricultural sustainability have been articulated in the publication “Towards Sustainabl... more Goals on agricultural sustainability have been articulated in the publication “Towards Sustainable Agricultural Systems in the 21st Century” (National Research Council). These goals include: 1. Farms must be profitable. 2. Farms must enhance environmental quality. 3. Farms must increase the quality of life for farmers and society. 4. Farms must produce enough to satisfy human needs. University of Maryland research has indicated that management-intensive grazing (MIG) dairy farms may achieve these goals better than conventional confinement (CC) dairy farms. Financial data collected from dairy farms indicates that MIG farms were more profitable than CC farms on a per cow, per milk-weight, and per acre basis for farms with less than 200 cows (Hanson, et.al. 2013). Profits of MIG farms were also less variable, so that MIG farms faced less income risk. Grazing has other benefits as well. Grazing seems to be much healthier for dairy cows. Veterinary, breeding, and medicine costs are much ...
Intercropping orchards with cover crops is an important practice for achieving sustainable soil m... more Intercropping orchards with cover crops is an important practice for achieving sustainable soil management. However, little research has addressed the development of a soil quality index (SQI) to evaluate cover crop effects on orchard soil quality. The aim of this study was to ascertain whether cover cropping improves soil quality and fruit yield of Goji (Lycium barbarum L.) while reducing or replacing organic fertilizer application. The main treatments were the traditional management of L. barbarum as a monocrop (M) and intercropping Goji with radish (Raphanus sativus L.) as an annual cover crop (I). Within the main treatments, different levels of organic fertilizer were applied at 0 kg·plant−1 (M0), 2 kg·plant−1 (M1), and 4 kg·plant−1 (M2). After six years of planting, we analyzed the changes in soil quality caused by cover cropping with different organic fertilizer levels based on the SQI method. Goji yields were used for validation of the SQI derived from a minimum data set of s...
Student evaluation can be greatly facilitated by using computer scored and analyzed multiple choi... more Student evaluation can be greatly facilitated by using computer scored and analyzed multiple choice tests. Test parameters can aid the instructor in the interpretation of student scores, and item analyses can provide him with valuable feedback for improving both teaching and writing. The caliber of testing influences the caliber of learning, and at college level it is more appropriate to evaluate complex learning outcomes than it is simply to test recall of information. Therefore we are justified in making an effort to evaluate attainment of higher levels of knowledge on multiple choice tests and to de~mphasize rote memorization. This paper describes ways of increasing the quality and usefulness of computer scored tests by examples from an introductory soil science course, The authors use test and item analysis; define the variable to be tested; and make a table of specifications to assure that the test reflects a balance, characteristic of the course, of both subject matter and level of knowledge. Most of their examples show how to write better test items, but they also give examples of ways to reduce the guessing factor and how to increase the value of the distractor. Some techniques for writing test items for high-level knowledge are: 1) using terms in problems rather than defining the terms, 2) presenting novel rather than familiar situations , 3} using problems that require applying knowledge , and 4) asking for interpretations of data requiring both knowledge and reasoning. A. T MANY land-grant universities, enrollments in basic agricultural science courses have increased dramatically over the past few years. Classes have jumped in size from 20 or 30 students to "megalectures" of several hundred students. Teaching methods have had to undergo considerable modification in order to cope with fundamental changes in the classroom situation. The challenge is to maintain or improve the quality of instruction and validity of student evaluation in these large classes. Among the diverse approaches taken by agronomist educators, certain practices seem to have gained widespread acceptance. One evaluation tool is the use of computer-scored achievement tests. At best this type of testing can result in fast, fair, and accurate evaluation of student achievement and readily accessible feedback on the progress of of the teaching process. At worst it reduces testing and achievement to the level of rote recall of un-connected facts. This paper discusses ways of increasing the quality and usefulness of computer scored tests used in …
Though the use of fertilizers can enhance productivity and increase profits for small-scale farmi... more Though the use of fertilizers can enhance productivity and increase profits for small-scale farming families, two barriers to their adoption have proved critical. First, many farmers often cannot afford to buy fertilizers; second, use recommendations from government sources may not be appropriate for specific farms. In Tanzania, 1 our multi-disciplinary team used low-cost soil testing to pair field-specific recommendations with subsidy vouchers to help cover the cost of fertilizer purchase. Our results show that farmers benefitted significantly in both yields and profits when (1) fertilizer recommendations were calibrated to the needs of individual farms and (2) a subsidy made the recommended fertilizers affordable
Cover crops can reduce nitrate leaching after cash crop harvest. Despite widespread cover crop im... more Cover crops can reduce nitrate leaching after cash crop harvest. Despite widespread cover crop implementation there has been a limited impact on water quality in the Chesapeake Bay watershed. We hypothesize that typical timing for Maryland cover crop planting after cash crop harvest is too late to allow roots to take up substantial nitrate from the soil profile before it is leached by winter drainage water. Across four site-years (including sandy and silty soils) we compared various planting dates for a radish (Raphanus sativus, L)-crimson clover (Trifolium incarnatum, L.)-triticale (Triticosecale) cover crop mixture. Also, across two site-years we compared early-planted pure rye, radish, and a 3-species mixture to no cover. We measured cover crop biomass and N content and used tension lysimeters to measure deep soil porewater nitrate concentrations. Cumulative nitrate leaching was estimated from these concentrations and weather-based drainage estimates. Cover crops were planted on four dates over a six-week period. Overall, cover crops planted first, second, third, fourth, and no cover crop (just weeds) resulted in 3340, 3160, 1600, 303, and 164 kg ha-1 of biomass, biomass N accumulation of 65.5, 68.6, 44.0, 9.88, and 4.79 kg N ha-1 , and mean porewater concentrations of 2.71, 2.57, 4.72, 10.0, 17.1 mg L-1 of nitrate-N, respectively. Over two site-years, the three-species mix performed as well or better than pure rye or radish. Early planting altered cover crop species proportions, increased cover crop productivity and reduced nitrate leaching from agricultural fields. This article is protected by copyright. All rights reserved.
Forage radish (Raphanus sativus L. var. longipinnatus) is an increasingly popular winter cover cr... more Forage radish (Raphanus sativus L. var. longipinnatus) is an increasingly popular winter cover crop in the mid-Atlantic region of the United States. This crop can be used to scavenge residual soil nitrate (NO 3 −) and ammonium (NH 4 +), with the goal of reducing nitrogen (N) loss from agricultural fields and increasing N availability for subsequent crops. In the present work, two sites in Maryland were examined to investigate the influence of forage radish cover crop and residual N fertilizer from corn side-dressing on the forms and vertical distribution of soil N and the yield of subsequent no-till silage corn (Zea mays L.). Forage radish dry matter ranged from 1,965 to 3,360 kg ha −1 for shoots and 1,531.5 to 3,740 kg ha −1 for fleshy taproots. Forage radish had a marked influence on the distribution of NO 3 −-N in the soil profile; in the spring following a radish cover crop, NO 3 −-N was concentrated in the surface soil, with no accumulation in deep soil, even at the highest fertilization rate of 168 kg N ha −1. The cover crop had no significant influence on the NH 4 +-N or total N profile. The average silage corn yield was significantly improved following cover cropping. In addition, the yield increased with the highest N fertilization rate but was not affected by low or medium N fertilization rate. In conclusion, a radish cover crop captures large quantities of residual N from the deep soil following N side-dressing and can improve the yield of subsequent silage.
Green and animal manures provide plant-available N (PAN) in annual cropping systems and contribut... more Green and animal manures provide plant-available N (PAN) in annual cropping systems and contribute to improved soil quality. Our objectives were to determine the effects of cover crop residue type and pelletized poultry litter (PPL) application method on: (i) the spatiotemporal distribution of topsoil mineral N (N min), (ii) the average topsoil N min at four developmental stages of corn (Zea mays L.), and (iii) corn N uptake. we collected soil and plant samples from a factorial experiment that included three cover crop residues: hairy vetch (Vicia villosa Roth), cereal rye (Secale cereale L.), and a hairy vetch/cereal rye mixture; and four PPL treatments: no PPL and 3.5 Mg PPL ha-1 either broadcast at planting, subsurface banded at the fifthleaf stage, or broadcast and incorporated at planting. Most of the N min in the broadcast treatment was concentrated near the soil surface, N min associated with the subsurface band remained within 10 cm of the delivery location throughout the growing season, while N min was distributed to a depth of 20 cm in the incorporated treatment. Average N min to 30 cm was significantly greater in soil with hairy vetch residue than in soil with cereal rye residue at emergence and the fifth-leaf stage, while the cover crop mixture had average N min levels intermediate between the monocultures or similar to cereal rye depending on the year. In both years, corn N uptake tended to be greatest with hairy vetch residue and broadcast or subsurface band PPL application, averaging 215 kg ha-1 across years in these treatments.
Dairy farm size has increased in the United States, while the profit margin has decreased. An alt... more Dairy farm size has increased in the United States, while the profit margin has decreased. An alternative to confined feeding dairy farming is management intensive grazing (MIG), a grass-based system relying on rotational grazing for most of the herd’s dietary requirements. Previous research has measured high levels of nitrate leaching under MIG, citing the liquid nature and high nitrogen (N) content of urine. However, this research included heavy N fertilizer applications or was conducted on monolith lysimeters with artificial leaching processes and did not accurately represent mid-Atlantic MIG dairy farms. Phosphorus (P) losses have typically been attributed to runoff and erosion but are now being ascribed to leaching as well. To measure the magnitude of N and P losses to groundwater, we sampled shallow groundwater and pore water on one confined feeding and two MIG-based Maryland dairy farms between 2001 and 2004. Transects of nested piezometers and ceramic-tipped suction lysimete...
A study aimed at the assessment of the contribution of pigeon pea roots to N yield for the pigeon... more A study aimed at the assessment of the contribution of pigeon pea roots to N yield for the pigeon pea was conducted at Chitedze Agricultural Research Station (S 13 0 59' 23.2", E033 0 38' 36.8"), Malawi in the 2012/2013 cropping season. Ten treatments, replicated three times were laid in a randomized complete block design. Two pigeon pea varieties, long (ICEAP 04000) and medium duration (ICEAP 00557) and groundnut (CG 7) were grown as monocultures and intercrops. The intercrops involved planting either of the pigeon pea varieties with groundnut. Some of the plots were treated with triple super phosphate (TSP) at the rate of 25 kg P ha-1. Analysis of soil samples collected in all treatment plots indicate that the soil had low fertility, having; low organic carbon (1.4 %), low cation exchange capacity (CEC) (NH4OAc) (3.5-3.6 cmol (+) kg-1 soil) and low N (0.12%), while plant available phosphorus (Mehlich 3) was marginally adequate both in the top and sub soil (μ=21.5...
As the name implies, a cover crop consists of plants grown primarily to keep the land covered, es... more As the name implies, a cover crop consists of plants grown primarily to keep the land covered, especially during the off-season or between cash crops. In temperate regions like most of Europe and North America, a cover crop sown immediately after the main crop harvest in fall is considered a winter cover crop. It will grow in the fall, either subjected to frost-kill or go into relative dormancy during the dead of winter, and then, if winter-hardy, recommence growth in very early spring before soils are warm and dry enough for the next cash crop. If the climate is sufficiently mild, such cover crops may produce substantial above-ground dry matter (3000–6000kg ha−1) and nearly complete ground cover before being terminated. For many decades, the use of cover crops
Journal of the Science of Food and Agriculture, 2021
BACKGROUND Soybeans (Glycine max) are a major protein source for both humans and non-ruminant liv... more BACKGROUND Soybeans (Glycine max) are a major protein source for both humans and non-ruminant livestock, however, the usability of soybean protein is limited by the concentration of the essential sulfur (S) containing amino acids methionine and cysteine (MET+CYS). Traditional efforts to improve protein quality in soybeans have largely been focused on plant breeding, but soil S fertility may also influence seed MET+CYS concentration. Crop S deficiencies are increasingly common due to soil depletion by high yields and reduced atmospheric deposition. We report on a survey of commercial soybean fields and two replicated split-plot field experiments in the mid-Atlantic region, USA. The experimental treatments were two levels (0 or 100 kg S ha-1 ) of broadcast gypsum (CaSO4 ) and two levels (0 or 11 kg-S ha-1 ) of foliar Epsom Salt (MgSO4 ) applied to two soybean cultivars. The objective was to assess the variability of, and effect of S fertilization on S and MET+CYS concentrations in soybean seeds. RESULTS Sulfur ranged from 2.35 to 3.54 mg g-1 and MET+CYS ranged from 5.5 to 9.2 mg g-1 protein in seeds from commercial fields surveyed. Sulfur application increased seed MET+CYS concentration 1.3 to 2.0-fold in two replicated field experiments. Overall, MET+CYS concentration in protein ranged from 3.9 to 12.8 mg g-1 and was linearly predicted (R2 = 0.65) by seed S. CONCLUSIONS Soybean seed S and MET+CYS concentrations vary widely. We show that field-scale S application can greatly enhance soybean MET+CYS content and therefore protein quality. This article is protected by copyright. All rights reserved.
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Papers by Raymond Weil