• Authors:
    • Liebig, M. A.
    • Merrill, S. D.
    • Krupinsky, J. M.
    • Tanaka, D. L.
    • Hanson, J. D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Producers need to know how to sequence crops to develop sustainable dynamic cropping systems that take advantage of inherent internal resources, such as crop synergism, nutrient cycling, and soil water, and capitalize on external resources, such as weather, markets, and government programs. The objective of our research was to determine influences of previous crop and crop residues (crop sequence) on relative seed and residue yield and precipitation-use efficiency (PUE) for the no-till production of buckwheat ( Fagopyrum esculentum Moench), canola ( Brassica napus L.), chickpea ( Cicer arietinum L.), corn ( Zea mays L.), dry pea ( Pisum sativum L.), grain sorghum ( Sorghum bicolor L.), lentil ( Lens culinaris Medik.), proso millet ( Panicum miliaceum L.), sunflower ( Helianthus annus L.), and spring wheat ( Triticum aestivum L.) grown in the northern Great Plains. Relative seed yield in 2003 for eight of the 10 crops resulted in synergistic effects when the previous crop was dry pea or lentil, compared with each crop grown on its own residue. Buckwheat, corn, and sunflower residues were antagonistic to chickpea relative seed yield. In 2004, highest relative seed yield for eight of the 10 crops occurred when dry pea was the previous crop. Relative residue yield followed a pattern similar to relative seed yield. The PUE overall means fluctuated for seven of the 10 crops both years, but those of dry pea, sunflower, and spring wheat remained somewhat constant, suggesting these crops may have mechanisms for consistent PUE and were not as dependent on growing season precipitation distribution as the other seven crops. Sustainable cropping systems in the northern Great Plains will approach an optimal scheme of crop sequencing by taking advantage of synergisms and avoiding antagonisms that occur among crops and previous crop residues.
  • Authors:
    • listed as anonymous
  • Source: Egyptian Journal of Plant Breeding
  • Volume: 11
  • Issue: 1
  • Year: 2007
  • Summary: These proceedings contain 30 papers on the various aspects of plant breeding including heterosis, combining ability and inheritance studies, characterization of cultivars, performance evaluation and genetic improvement of field crops (including wheat, cotton, soyabean, maize, rice, barley, rape, sorghum and faba bean) and horticultural crops (e.g. mango, tomato, pepper and grape).
  • Authors:
    • Awasthi, V. B.
  • Source: Agricultural insect pests and their control
  • Year: 2007
  • Summary: This book, which contains 24 chapters, covers the morphology (integument, head, thorax and abdomen), physiology (digestive system, circulatory system, excretory system, respiratory system, nervous system, photoreceptors, endocrine system, and reproductive system), development and metamorphosis, and control (through physical, mechanical, biological, chemical and integrated management strategies, and through quarantine and the use of pheromones) of agricultural insect pests. An overview of the life history and control of pests of cotton and fibre crops, sugarcane, oilseed crops, pulse crops, sorghum, cereals, fruits and fruit trees, vegetables, plantation crops, soyabean, ornamental plants, and stored grains is provided. This book is intended for students of agricultural entomology in India, but will also be useful for those who are preparing for examinations for admission in government agencies.
  • Authors:
    • Mentreddy, R. S.
    • Cebert, E.
    • Kumar, S.
    • Bishnoi, U. R.
  • Source: World Journal of Agricultural Sciences
  • Volume: 3
  • Issue: 3
  • Year: 2007
  • Summary: In the southeastern USA, winter rape in addition to winter wheat can become another commercial crop with benefits such as breaking of disease and insect cycles caused by continuous wheat cropping. Information on agronomic production practices and comparative profitability of rape and wheat for the southeastern USA is lacking. Therefore, from 1998 to 2005, a series of field experiments were conducted on rape to determine the optimum planting date, seeding, nitrogen and sulfur rates, rotation suitability with summer crops and comparative economic value to winter wheat. Results from three planting dates, three seeding rates and four nitrogen rates experiments showed that rape planted in early October produced significantly higher seed yield (3204 kg/ha) than from mid to late October 10-15 (2362 and 2058 kg/ha) plantings. The seeding rate of 6.0 kg/ha and 180 kg N/ha gave the highest (3779 kg/ha) seed yield. Rape response to sulfur application was significant and highest seed yield (3259 kg/ha) was obtained with 30 kg S/ha along with 228 kg N/ha. As a rotation crop after soyabean and maize, rape gave significantly higher yields of 3129 and 2938 kg/ha, respectively, than when planted after cotton (2521 kg/ha) or grain sorghum (2650 kg/ha). Both winter rape and wheat produced similar yields of 2.6 and 2.9 t/ha, respectively. As grain crop, canola with its higher price fetched $220/ha compared to $109/ha from wheat, however, this profitability is almost equal when income from wheat straw was added to that from grain.
  • Authors:
    • Hergert, G. W.
    • Tarkalson, D. D.
    • Cassman, K. G.
  • Source: Agronomy Journal
  • Volume: 98
  • Issue: 1
  • Year: 2006
  • Summary: Tillage systems and nutrient management influence soil chemical properties that can impact the long-term sustainability of dryland production systems. This study was conducted to compare the effects of no-till (NT) and conventional till (CT) on the soil chemical properties and grain yield of a dryland winter wheat ( Triticum aestivum L.)-grain sorghum [ Sorghum bicolor (L.) Moench]/corn ( Zea mays L.)-fallow rotation. The effects of tillage practice over a 27-yr period (1962-1989) and the effect of the conversion of CT to NT over a 14-yr period (1989-2003) on selected soil chemical properties [pH, cation exchange capacity (CEC), base saturation (BS), soil organic C (SOC), K, Ca, Mg, and Bray-P] at different soil depths was determined. The acidification rate of the NT treatment from 1962 to 2003 was also determined. The study was conducted at North Platte, NE on a Holdrege silt loam (fine-silty, mixed, mesic Typic Argiustolls). In 1989, there were differences in soil chemical properties between CT and NT at some depths after 27 yr. However, in 2003, 14 yr after converting from CT to NT, there were no differences in the soil chemical properties compared with continuous NT. In 1989 and 2003, the soil chemical properties varied with soil depth. The acidification rate from 1962 to 2003 for the NT treatment in the 0- to 15-cm depth was 1.3 kmol H + ha -1 yr -1. This rate of acidification represents 38% of the total potential acidity from N fertilizer applications over 41 yr. Acidification was attributed to nitrification of ammonium-based fertilizers and leaching of NO 3-. Long-term winter wheat (1966-1983) and grain sorghum (1964-1988) grain yields were higher for NT (2718 and 4125 kg ha -1) than CT (2421 and 3062 kg ha -1). Retention of soil moisture as a result of increased residue cover under NT likely contributed to higher NT yields. Soil chemical properties in the wheat-sorghum/corn-fallow rotation will likely continue to change as a result of current management practices. Lime additions may become necessary in the future to ensure the sustainability of crop production in this system.
  • Authors:
    • Cassman, K. G.
    • Hergert, G. W.
    • Payero, J. O.
    • Tarkalson, D. D.
  • Source: Plant and Soil
  • Volume: 283
  • Issue: 1-2
  • Year: 2006
  • Summary: Soil pH is decreasing in many soils in the semiarid Great Plains of the United States under dry land no-till (NT) cropping systems. This study was conducted to determine the rate of acidification and the causes of the acidification of a soil cropped to a winter wheat (Triticum aestivum L.)-grain sorghum [Sorghum bicolor (L.) Moench]/corn (Zea mays L.)-fallow rotation (W-S/C-F) under NT. The study was conducted from 1989 to 2003 on soil with a long-term history of either continuous NT management [NT(LT)] (1962-2003) or conventional tillage (CT) (1962-1988) then converted to NT [NT(C)] (1989-2003). Nitrogen was applied as ammonium nitrate (AN) at a rate of 23 kg N ha(-1)supercript stop in 1989 and as urea ammonium nitrate (UAN) at an average annual rate of 50 kg N ha(-1) from 1990 to 2003 for both NT treatments. Soil samples were collected at depth increments of 0-5, 5-10, 10-15, and 15-30 cm in the spring of 1989 and 2003. Acidification rates for the NT(LT) and NT(C) treatments were 1.13 and 1.48 kmol H+ ha(-1) yr(-1) in the 0-30 cm depth, respectively. The amount of CaCO3 needed to neutralize the acidification is 57 and 74 kg ha(-1) yr(-1) for the NT(LT) and NT(C) treatments, respectively. A proton budget estimated by the Helyar and Porter [1989, Soil Acidity and Plant Growth, Academic Press] method indicated that NO3- leaching from the 30 cm depth was a primary cause of long-term acidification in this soil. Nitrate leaching accounted for 59 and 66% of the H+ from the acid causing factors for NT(LT) and NT(C) treatments, respectively. The addition of crop residues to the soil neutralized 62 and 47% of the acidity produced from the leaching of NO3-, and 37 and 31% of the acid resulting from NO3- leaching and the other acid-causing constituents for the NT(LT) and NT(C) treatments, respectively. These results document that surface soils in dry land W-S/C-F rotations under NT are acidifying under current management practices. Improved management to increase nitrogen uptake efficiency from applied fertilizer would help reduce the rate of acidification. The addition of lime materials to prevent negative impacts on grain yields may be necessary in the future under current management practices.
  • Authors:
    • McVay, K.
    • Langemeier, M.
    • Regehr, D.
    • Devlin, D.
    • Mankin, K.
    • Pierzynski, G.
    • Sweeney, D.
    • Janssen, K.
    • Zeimen, M.
  • Source: Journal of Soil and Water Conservation
  • Volume: 61
  • Issue: 5
  • Year: 2006
  • Summary: Best management practices have been recommended for controlling nutrient, herbicide, or sediment losses with surface runoff. This study was designed to determine the best overall combination of tillage and application practices to reduce surface losses from cropland. Runoff was collected from two Kansas sites in sorghum-soybean rotation during the 2001 to 2004 crop years and analysed for bioavailable phosphorus (P), soluble P, total P, ammonium, nitrate, total nitrogen (N), sediment, atrazine, and metolachlor concentrations. No-till treatments consistently experienced higher runoff water volumes than the chisel/disk tillage system used to warm and dry these clay soils in the spring. For this reason the no-till treatments also had higher nutrient and herbicide losses than chisel/disk tillage regardless of use of high or low application management techniques. The high included fertilizer and herbicide application practices intended to reduce losses with runoff while the standard application broadcast applied fertilizer and herbicide at planting. Few consistent differences were seen for pollutant loss between the high and standard application management. When average losses for all eight location-years were compared to chisel/disk low, soluble P losses were 3.0 and 2.1 times higher for no-till low and no-till high, respectively; metolachlor losses were 2.4 and 2.7 times higher for no-till low and no-till high, respectively; and atrazine losses were 4.8 and 6.1 times higher for no-till low and no-till high, respectively. The chisel/disk low did experience two times higher sediment losses compared with the no-till low or no-till high, when averaging over all eight location-years. However, tolerable soil loss was not exceeded, chisel/disk low generally had small losses for all tested pollutants and may be the best management combination to simultaneously reduce nutrient, herbicide, and sediment losses with cropland runoff for sites like those used in this study.
  • Authors:
    • Cantero-Martinez, C.
    • Westfall, D. G.
    • Sherrod, L. A.
    • Peterson, G. A.
  • Source: Journal of Soil and Water Conservation
  • Volume: 61
  • Issue: 2
  • Year: 2006
  • Summary: The presence of crop residue is an important component of dryland cropping systems management in the semiarid environment where soil erosion by wind is a major soil degradation process. Residue also affects precipitation capture and runoff. Long-term residue quantity dynamics of different cropping systems has not been studied in the semi-arid environment of the western Great Plains. Long-term studies were conducted in eastern Colorado, USA to determine the interaction of no-till cropping systems, soils, and climatic gradient on the production, retention, and disappearance of crop residue over a 12-year period. The cropping systems evaluated were winter wheat ( Triticum aestivum)-summer fallow (WF), winter wheat-maize ( Zea mays) or sorghum ( Sorghum bicolor)-summer fallow (WC/SF), winter wheat-maize/sorghum-millet ( Panicum miliaceum)-summer fallow (WC/SMF), and continuous cropping (CC). A soil surface residue base was achieved in a few years (four to five) and changed little over time. However, as cropping intensity increased the total crop residue retained on the soil surface increased as the proportion of fallow time decreased; a general trend was for residue levels to increase slowly. However, in the winter wheat-summer fallow system residue levels showed a trend to decrease after the initial base was achieved. Greater residue production and retention occurred on the toeslope soil position because these soils are deeper, have greater water holding capacity, and receive run-on water from upslope positions. Residue disappearance was less in the fallow period before maize planting compared to before wheat planting due to the greater fallow period, which included summer fallow in the wheat system. Residue loss was greater during the crop production periods as compared to the fallow periods. The levels of residue present on the soil surface in our intensive no-till cropping systems were generally adequate to control erosion by wind. However, at our high potential evapotranspiration site the residue levels were "marginal" for adequate wind erosion abatement, particularly in the winter wheat-summer fallow system. A combination of no-till management and increased cropping intensity (greater than winter wheat-summer fallow) is the key to sustainable production and soil conservation in this semi-arid environment.
  • Authors:
    • Drinkwater, L. E.
    • David, M. B.
    • Tonitto, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 112
  • Issue: 1
  • Year: 2006
  • Summary: The availability of Haber-Bosch nitrogen (N) has permitted agricultural intensification and increased the productive capacity of agroecosystems; however, approximately 50% of this applied fertilizer N is lost from agricultural landscapes. Extensive efforts have been devoted to improving the N use efficiency of these systems. Diversified crop rotations using cover crops to provide a variety of ecosystem functions, including biological N fixation (BNF), could maintain yields while reducing N losses. Although leguminous plants used as green manures are capable of fixing N in quantities which exceed cash crop demand, the prospect of replacing significant quantities of Haber-Bosch N with BNF is widely viewed as impractical due to yield reductions. Likewise, the practice of replacing bare fallows with non-leguminous cover crops in systems receiving Haber-Bosch N is generally deemed not economically viable. We conducted a quantitative assessment of cash crop yields and N retention in rotations that implemented these practices. We performed a meta-analysis on experiments comparing crop yield, nitrate leaching, or soil nitrate between conventional (receiving inorganic fertilizer with a winter bare fallow) and diversified systems managed using either a non-legume over-wintering cover crop (amended with inorganic fertilizer) or a legume over-wintering cover crop (no additional N fertilizer). Only studies with rotations designed to produce a cash crop every year were included in our analysis. Many yield comparisons were found in the literature, but only a limited number of nitrate leaching or soil inorganic N studies met the criteria for inclusion in a meta-analysis. Long-term studies were also uncommon, with most data coming from experiments lasting 2-3 years. Yields under non-legume cover crop management were not significantly different from those in the conventional, bare fallow systems, while leaching was reduced by 70% on average. Relative to yields following conventional N-fertilization, the legume-fertilized crops averaged 10% lower yields. However, yields under green manure fertilization were not significantly different relative to conventional systems when legume biomass provided >=110 kg N ha-1. On average, nitrate leaching was reduced by 40% in legume-based systems relative to conventional fertilizer-based systems. Post-harvest soil nitrate status, a measure of potential N loss, was similar in conventional and green manure systems suggesting that reductions in leaching losses were largely due to avoidance of bare fallow periods. These results demonstrate the potential for diversified rotations using N- and non-N-fixing cover crops to maintain crop yields while reducing the anthropogenic contributions to reactive N fluxes.
  • Authors:
    • Varvel, G. E.
  • Source: Soil Science Society of America Journal
  • Volume: 70
  • Issue: 2
  • Year: 2006
  • Summary: Sequestration and storage of carbon (C) by agricultural soils has been cited as one potential part of the solution to soil degradation and global climate change. However, C sequestration in soils is a slow and dynamic process. The objective of this study was to evaluate the effects of crop rotation and N fertilizer management on soil organic C (SOC) levels at several points in time during 18 yr of a long-term study in the Western Corn Belt. Seven cropping systems (three monoculture, two 2-yr, and two 4-yr rotations) with three levels of N fertilizer were compared. Soil samples were taken in the spring in 1984, 1992, 1998, and 2002 to a depth of 30 cm in 0- to 7.5-, 7.5- to 15-, and 15- to 30-cm increments. No differences were obtained in SOC levels in 1984 at the beginning of the study. After 8 yr, rotation significantly increased SOC 449 kg ha-1 across all cropping systems. From 1992 to 2002, SOC levels in the 0- to 7.5-cm depth decreased by 516 kg ha-1 across all cropping systems. Soil organic C levels in the 7.5- to 15-cm depths in 1992 and 2002 demonstrated similar rotation effects to those in the surface 0- to 7.5-cm, being not significantly affected from 1984 to 1992 but being significantly decreased from 1992 to 2002 (568 kg SOC ha-1 across all cropping systems). Many of the SOC gains in the surface 30 cm measured during the first 8 yr of the study were lost during the next 10 yr in all but the 4-yr cropping systems after 18 yr. The loss of SOC in this latter period occurred when depth of tillage was increased by using a tandem disk with larger-diameter disks. These results demonstrate that more than one point-in-time measurement from long-term experiments is necessary to monitor SOC changes when several management variables, such as cropping system and N fertilizer, are being used. They also indicate that apparent small changes in cultural practices, such as in depth of tillage in this experiment, can significantly change SOC dynamics in the soil. Subtle changes in cultural practices (e.g., tillage depth) can have significant long-term results, but long-term experiments are required to quantify their impact under variable climatic conditions.