• 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:
    • Caswell, M.
    • Fernandez-Cornejo, J.
  • Source: Economic Information Bulletin Number 11
  • Volume: 11
  • Year: 2006
  • Authors:
    • Hunt, P. G.
    • Novak, J. M.
    • Frederick, J. R.
    • Bauer, P. J.
  • Source: Soil & Tillage Research
  • Volume: 90
  • Issue: 1-2
  • Year: 2006
  • Summary: Tillage affects the ability of coarse-textured soils of the southeastern USA to sequester C. Our objectives were to compare tillage methods for soil CO2 flux, and determine if chemical or physical properties after 25 years of conventional or conservation tillage correlated with flux rates. Data were collected for several weeks during June and July in 2003, October and November in 2003, and April to July in 2004 from a tillage study established in 1978 on a Norfolk loamy sand (fine-loamy, kaolinitic, thermic Typic Kandiudults). Conventional tillage consisted of disking to a depth of approximately 15 cm followed by smoothing with an S-tined harrow equipped with rolling baskets. Conservation tillage consisted of direct seeding into surface residues. Flux rates in conservation tillage averaged 0.84 g CO2 m-2 h-1 in Summer 2003, 0.36 g CO2 m-2 h-1 in Fall 2003, 0.46 g CO2 m-2 h-1 in Spring 2004, and 0.86 g CO2 m-2 h-1 in Summer 2004. Flux rates from conventional tillage were greater for most measurement times. Conversely, water content of the surface soil layer (6.5 cm) was almost always higher with conservation tillage. Soil CO2 flux was highly correlated with soil water content only in conventional tillage. In conservation tillage, no significant correlations occurred between soil CO2 flux and soil N, C, C:N ratio, pH, bulk density, sand fraction, or clay fraction of the surface 7.5 cm. In conventional tillage, sand fraction was positively correlated, while bulk density and clay fraction were negatively correlated with soil CO2 flux rate, but only when the soil was moist. Long-term conservation tillage management resulted in more uniform within- and across-season soil CO2 flux rates that were less affected by precipitation events.
  • Authors:
    • Marchetti, M.
    • Vitorino, A.
    • Souza, L.
    • Brandt, E.
  • Source: CIENCIA E AGROTECNOLOGIA
  • Volume: 30
  • Issue: 5
  • Year: 2006
  • Summary: The effects of crop rotation on the performance of soyabean were studied in Dourados, Mato Grosso do Sul, Brazil, during 1998, 1999 and 2000. The treatments were: maize/vetch/maize/vetch/soyabean, cotton/oat/cotton/sorghum/soyabean, soyabean/wheat/soyabean/maize/millet/soyabean, maize/grazing turnip/maize/sorghum/soyabean, maize/oat/maize/bean/millet/soyabean, rice/grazing turnip/rice/oat/soyabean, rice/sorghum/rice/bean/millet/soyabean, cotton/wheat/cotton/wheat/soyabean, and cotton/grazing turnip/cotton/oat/soyabean. Dry matter of aerial parts at the full flowering stage, plant height, first pod insertion, number of pods per plant, productivity and 1000-grain mass were evaluated. The rotation system had no significant effects on plant height, first pod insertion, and number of pods per plant. The highest grain yields were obtained under rice/sorghum/rice/bean/millet/soyabean and soyabean/wheat/soyabean/maize/millet/soyabean.
  • Authors:
    • Prasad, J.
    • Challa, O.
    • Mandal, C.
    • Mandal, D. K.
  • Source: Agropedology
  • Volume: 16
  • Issue: 2
  • Year: 2006
  • Summary: The present study used water use efficiency (WUE) as an indicator of land quality index (LQI), through a composite Water Use Efficiency (GMWUE), on the line of land evaluation index of Food and Agriculture Organization. The GMWUE is a multiplicative function of WUE of individual crop/cropping system raised within a micro agro-edaphic environment (AEE). A relative LQI scale has been developed considering LQI for the most productive land as 100 and accordingly the LQI of other land has been fixed. The experimental cropping systems were cotton (sole), sorghum-wheat, soyabean-wheat, sorghum-gram and soyabean-gram for two years under normal rainfall in typical shrink-swell soils of Nagpur district of Maharashtra, India. The soyabean-wheat system had highest water use (WU) of 586.8 to 755.9 mm followed by sorghum-wheat, soyabean-gram, sorghum-gram and sole cotton. The WUE was highest for sole cotton (4.8-11.5 kg ha -1 mm -1) followed by soyabean-gram (3.7-10.16 kg ha -1 mm -1). The LQI in terms of GMWUE was 100 for Vertic Haplustepts occurring in the lower piedmont plain whereas it was 51 for Typic Haplustepts and 48 for Typic Haplusterts representing the upper piedmont and valley plain, respectively.
  • Authors:
    • Kumar, P.
    • Yadav, S. K.
    • Kumar, M.
    • Rinwa, R . S.
  • Source: Haryana Journal of Horticultural Sciences
  • Volume: 35
  • Issue: 3/4
  • Year: 2006
  • Summary: An experiment was conducted during 2003-04 and 2004-05 to study the nitrogen, phosphorus and potassium uptake by different cropping systems in semiarid tract of Haryana, India. The experiment comprised 7 cropping systems, viz., pearl millet-wheat, pearl millet-mustard, soyabean-wheat-cowpea, sorghum-wheat, pearl millet-potato-green gram, pearl millet-field pea-maize, and cotton-wheat. The uptake of nitrogen, phosphorus and potassium by the crops varied among different cropping systems. The nutrient uptake was higher in high yielding cropping systems. The nutrients uptake was highest in pearl millet-potato-green gram cropping system.
  • Authors:
    • Tolbert, V. R.
    • Mays, D. A.
    • Nyakatawa, E. Z.
    • Green, T. H.
    • Bingham, L.
  • Source: Biomass and Bioenergy
  • Volume: 30
  • Issue: 7
  • Year: 2006
  • Summary: Renewable energy sources such as bioenergy crops have significant potential as alternatives to fossil fuels. Potential environmental problems arising from soil sediment and nutrient losses in runoff water from bioenergy crops need to be evaluated in order to determine the sustainability and overall feasibility of implementing bioenergy development strategies. This paper discusses runoff, sediment, N, and total P losses from agricultural land (continuous cotton (Gossypium hirsutum L.)) converted to short-rotation sweetgum (Liquidamber styraciflua L.) plantations with and without fescue (Festuca elatior L.) and switchgrass (Panicum virgatum L.) bioenergy crops, compared to corn (Zea mays L.), on a Decatur silt loam soil in north Alabama, from 1995 to 1999. Runoff volume was significantly correlated to total rainfall and sediment yield in each year, but treatment differences were not significant. Sweetgum plots produced the highest mean sediment yield of up to 800 kg ha(-1) compared to corn and switchgrass plots, which averaged less than 200 kg ha(-1). Runoff NH4+ N losses averaged over treatments and years for spring season (3.1 kg ha(-1)) were three to five times those for summer, fall, and winter seasons. Runoff NO3- N for no-till corn and switchgrass plots in spring and summer were five to ten times that for sweetgum plots. No-till corn and switchgrass treatments had 2.4 and 2.1 kg ha(-1) average runoff total P, respectively, which were two to three times that for sweetgum treatments. Growing sweetgum with a fescue cover crop provides significantly lower risk of water pollution from sediment, runoff NH4+ N, and NO3- N. (c) 2006 Published by Elsevier Ltd.
  • Authors:
    • Lohr, L.
    • Paudel, K. P.
    • Cabrera, M.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 21
  • Issue: 2
  • Year: 2006
  • Summary: Cotton production is the number one crop enterprise in Georgia in terms of revenue generation. However, due to continuous deterioration of soil quality with conventional tillage and chemical fertilizer application, the economic viability and sustainability of cotton production in Georgia are questionable. Residue management systems (RMSs) comprising winter cover crops were analyzed as an alternative to the existing system, which consists of conventional tillage and chemical fertilizer using yield benefit, net revenue, carbon sequestration, and yield efficiency criteria. Four different RMSs were examined for profitability and input efficiency. Four RMSs encompassing tillage versus no-till and chemical versus organic sources of plant nutrients were compared for their yield and net return differences. No-till and poultry litter with a cover crop was the only system with a positive return and crop yield based on the results from experimental data. Limited results from the experimental field were reinforced using a simulation study. When cotton yield is simulated with an alternative level of organic matter and nitrogen application, production function shows efficiency in input application at the higher level of organic matter. Regression results based on an erosion productivity impact calculator/environmental policy integrated climate (EPIC) simulation indicated that, in the long term, a no-till and poultry litter system may have promise in the region. The results from simulation confirm the results from the experimental study. This study reflected a need to change the cotton management system from the 200-year-old practice of employing intensively cultivated conventional tillage and chemical fertilizers to a new renewable resource-based system where residue management and organic sources of nutrients would be the key components.
  • Authors:
    • Whitehead, W. F.
    • Singh, B. P.
    • Sainju, U. M.
    • Wang, S.
  • Source: Journal of Environmental Quality
  • Volume: 35
  • Issue: 4
  • Year: 2006
  • Summary: Soil carbon (C) sequestration in tilled and nontilled areas can be influenced by crop management practices due to differences in plant C inputs and their rate of mineralization. We examined the influence of four cover crops (legume [hairy vetch (Vicia villosa Roth)], non-legume [rye (Secale cereale L.)], biculture of legume and nonlegume (vetch and rye), and no cover crops (or winter weeds)) and three nitrogen (N) fertilization rates (0, 60 to 65, and 120 to 130 kg N ha(-1)) on C inputs from cover crops, cotton (Gossypium hirsutum L.), and sorghum [Sorghum bicolor (L.) Moench)], and soil organic carbon (SOC) at the 0- to 120-cm depth in tilled and nontilled areas. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic Plinthic Paleudults) from 1999 to 2002 in central Georgia. Total C inputs to the soil from cover crops, cotton, and sorghum from 2000 to 2002 ranged from 6.8 to 22.8 Mg ha(-1). The SOC at 0 to 10 cm fluctuated with C input from October 1999 to November 2002 and was greater from cover crops than from weeds in no-tilled plots. In contrast, SOC values at 10 to 30 em in no-tilled and at 0 to 60 cm in chisel-tilled plots were greater for biculture than for weeds. As a result, C at 0 to 30 cm was sequestered at rates of 267, 33, -133, and -967 kg C ha(-1) yr(-1) for biculture, rye, vetch, and weeds, respectively, in the no-tilled plot. In strip-tilled and chisel-tilled plots, SOC at 0 to 30 cm decreased at rates of 233 to 1233 kg C ha(-1) yr(-1). The SOC at 0 to 30 cm increased more in cover crops with 120 to 130 kg N ha(-1) yr(-1) than in weeds with 0 kg N ha(-1) yr(-1) regardless of tillage. In the subtropical humid region of the southeastern United States, cover crops and N fertilization can increase the amount of C input and storage in tilled and nontilled soils, and hairy vetch and rye biculture was more effective in sequestering C than monocultures or no cover crop.
  • Authors:
    • Franzluebbers, A. J.
    • Causarano, H. J.
    • Reeves, D. W.
    • Shaw, J. N.
  • Source: Journal of Environmental Quality
  • Volume: 35
  • Issue: 4
  • Year: 2006
  • Summary: Past agricultural management practices have contributed to the loss of soil organic carbon (SOC) and emission of greenhouse gases (e.g., carbon dioxide and nitrous oxide). Fortunately, however, conservation-oriented agricultural management systems can be, and have been, developed to sequester SOC, improve soil quality, and increase crop productivity. Our objectives were to (i) review literature related to SOC sequestration in cotton (Gossypium hirsutum L.) production systems, (ii) recommend best management practices to sequester SOC, and (iii) outline the current political scenario and future probabilities for cotton producers to benefit from SOC sequestration. From a review of 20 studies in the region, SOC increased with no tillage compared with conventional tillage by 0.48 +/- 0.56 Mg C ha(-1) yr(-1) (H(0): no change,p