• Authors:
    • Kadasrivenkata, H.
    • Kapanigowda, M.
    • Stewart, B. A.
    • Howell, T. A.
    • Baumhardt, R. L.
  • Source: Field Crops Research
  • Volume: 118
  • Issue: 2
  • Year: 2010
  • Summary: Under dryland conditions of the Texas High Plains, maize ( Zea mays) production is limited by sparse and erratic precipitation that results in severe water stress particularly during grain formation. When plant populations are reduced to 2.0-3.0 plants m -2 to conserve soil water for use during grain filling, tillers often form during the vegetative growth and negate the expected economic benefit. We hypothesized that growing maize in clumps spaced 1.0 m apart would reduce tiller formation, increase mutual shading among the plants, and conserve soil water for grain filling that would result in higher grain yield. Studies were conducted during 2006 and 2007 at Bushland, TX. with two planting geometries (clump vs. equidistant), two irrigation methods (low-energy precision applicator, LEPA, and low-elevation spray applicator, LESA) at three irrigation levels (dryland, 75 mm and 125 mm in 2006; and dryland, 50 mm and 100 mm in 2007). For dryland plots in 2007, clump plants had only 0.17 tillers (0.66 tillers m -2) compared with 1.56 tillers per plant (6.08 tillers m -2) for equidistant spacing. Tillers accounted for 10% of the stover for the equidistant plants, but less than 3% of the grain. Clump planting produced significantly greater grain yields (321 g m -2 vs. 225 g m -2 and 454 g m -2 vs. 292 g m -2 during 2006 and 2007, respectively) and Harvest Indexes (0.54 vs. 0.49 and 0.52 vs. 0.39 during 2006 and 2007, respectively) compared with equidistant plants in dryland conditions. Water use efficiency (WUE) measurements in 2007 indicated that clumps had a lower evapotranspiration (ET) threshold for initiating grain production, but the production function slopes were 2.5 kg m -3 for equidistant treatments compared to 2.0 kg m -3 for clump treatments. There was no yield difference for method of irrigation on water use efficiency. Our results suggest that growing maize in clumps compared with equidistant spacing reduced the number of tillers, early vegetative growth, and Leaf Area Index (LAI) so that more soil water was available during the grain filling stage. This may be a useful strategy for growing maize with low plant populations in dryland areas where severe water stress is common.
  • Authors:
    • Keleman, A.
  • Source: Agriculture and Human Values
  • Volume: 27
  • Issue: 1
  • Year: 2010
  • Summary: One of the major adjustments brought on by the North American Free Trade Agreement (NAFTA) was a change in the relationship between Mexican agricultural support institutions and the small-scale agricultural sector. Post-NAFTA restructuring programs sought to correct previous inefficiencies in this sector, but they have also had the effect of marginalizing the producers who steward and manage the country's reserve of maize ( Zea mays) genetic diversity. Framed by research suggesting that certain maize varieties in a rain-fed farming region in southern Sonora are in danger of loss due chiefly to long-term drought, this article explores the ramifications of post-NAFTA agricultural policies for in situ maize diversity conservation. Qualitative methods, including semi-structured interviews with agricultural support institutions and participant observation with farmers, were used to gather data on dryland farmers' access to research and extension, as well as possibilities for collective action. In southern Sonora, agricultural support is oriented primarily toward high-tech production, and there are structural barriers to small-scale farmers' access to research and extension institutions. Further, collective action around agriculture is limited. These circumstances represent significant limitations to farmers' options for accessing new techniques which might help maintain maize diversity in the context of economic and environmental change.
  • Authors:
    • Clay, D. E.
    • Carlson, C. G.
    • Clay, S. A.
    • Reicks, G.
    • Kim, K.
    • Mamani-Pati, F.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 6
  • Year: 2010
  • Summary: The harvesting of plant biomass in excess of the soil organic carbon (SOC) maintenance requirement can produce short-term economic benefits at the cost of long-term sustainability. The objective of this study was to assess the impact of corn ( Zea mays L.) harvesting approach, N rate, and simulated landscape positions on estimated long-term SOC maintenance, profitability, and the energy efficiency of no-till corn grown in eastern South Dakota. The 3-yr experiment (2002-2004) contained four N rates (0, 56, 112, and 168 kg N ha -1), two simulated landscape positions (shoulder and backslope), and two harvesting methods (grain with 100% stover returned or grain+40% corn stover returned). No-tillage was used at the site. Energy gains (out-input), for a cropping system where corn grain or corn grain plus stover was sold for ethanol production, were calculated. Profitability was estimated and SOC turnover was simulated using the annual time-step model, SOC t=SOC t-1+k NHCNHC-k soc SOC t-1, where SOC t was SOC at time t, SOC t-1 was SOC at the sampling date before time t, k NHC was rate that nonharvested carbon (NHC) was converted to SOC, and k soc was the rate that SOC was converted to CO 2 Tillage impacts on k SOC was estimated with the model k soc [g SOC-C (g SOC year) -1]=0.0115+0.00631(tillage events). When only grain was harvested, the highest and lowest energy gains and financial were associated with the 112 kg N ha -1 (46.6 GJ ha -1 and $427 ha -1) and the 0 kg N per ha -1 (37.5 GJ ha -1 and $192 ha -1) treatments, respectively. Applying more than 112 kg N ha -1 did not increase energy gains or financial returns. Profits were increased by 60% when corn stover was harvested for ethanol production and lower yielding simulated shoulder/summit position had a lower energy gain (59.3 GJ ha -1 and $425 ha -1) and financial return than the backslope position (66.3 GJ ha -1 and $614 ha -1). The SOC sustainability analysis suggests that the ability of a system to maintain SOC depends on many factors including the amount of nonharvested carbon returned to the site, and the amount of carbon contained in the soil.
  • Authors:
    • Qin, L.
    • Shuang, L.
    • Wenquing, H.
    • Xurong, M.
    • Hoogenboom, G.
    • Changrong, Y.
    • Jiantao, D.
    • Ahmad, M.
    • Nangia, V.
  • Source: International Journal of Agricultural and Biological Engineering
  • Volume: 3
  • Issue: 2
  • Year: 2010
  • Summary: In the dryland regions of North China, water is the limiting factor for rainfed crop production. Conservation agriculture (featuring reduced or zero tillage, mulching, crop rotations and cover crops) has been proposed to improve soil and water conservation and enhance yields in these areas. Conservation agriculture systems typically result in increased crop water availability and agro-ecosystem productivity, and reduced soil erosion. To evaluate the potential of conservation agriculture to improve soil water balance and agricultural productivity, the DSSAT crop model was calibrated using the data of a field experiment in Shouyang County in the semi-arid northeastern part of the Yellow River Basin. The average annual precipitation at the site is 472 mm, 75% of which falls during the growing season. The site had a maize-fallow-maize rotation, data from two crop seasons (2005 and 2006) and four treatments for calibration and analysis were used. The treatments were: conventional tillage (CT), no-till with straw mulching (NTSM), all-straw incorporated (ASRT) and one-third residue left on the surface with no-till (RRT). The calibration results gave satisfactory agreement between field observed and model predicted values for crop yield for all treatments except RRT treatment, and for soil water content of different layers in the 150 cm soil profile for all treatments. The difference between observed and predicted values was in the range of 3%-25% for maize yield and RMSE was in the range of 0.03-0.06 cm 3/cm 3 for soil water content measured periodically each cropping season. While these results are encouraging, more rigorous calibration and independent model evaluation are warranted prior to making recommendations based on model simulations. Medium-term simulations (1995-2004) were conducted for three of the treatments using the calibrated model. The NTSM and ASRT treatments had similar or higher yields (by up to 36%), higher crop water productivity by up to 28% and reduced runoff of up to 93% or 43 mm compared to CT treatment.
  • Authors:
    • Ouedraogo, E.
    • Mando, A.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil Solutions for a Changing World
  • Year: 2010
  • Summary: A field experiment was conducted in Gampela (Burkina Faso) in 2000 and 2001 to assess the impact of organic and mineral sources of nutrients and combinations thereof in optimizing crop production under till and no-till and to assess the economic benefit of that option. At a dose equivalent to 40 kg N/ha, crop yield was better secured with organic-N than with urea-N. Combining organic and mineral sources of nutrients do not have only additive effects but real interaction, which significantly affect crop yield and water use efficiency. The use of soil and water management measures is a key to increase the economic benefit of mineral, organic or combined organic and mineral sources of nutrient application under semi-arid conditions.
  • Authors:
    • Schroeder, K. L.
    • Paulitz, T. C.
    • Schillinger, W. F.
  • Source: Plant Disease
  • Volume: 94
  • Issue: 1
  • Year: 2010
  • Summary: An irrigated cropping systems experiment was conducted for 6 years in east-central Washington State to examine agronomic and economic alternatives to continuous annual winter wheat ( Triticum aestivum) with burning and plowing, and to determine how root diseases of cereals are influenced by management practices. The continuous winter wheat treatment with burning and plowing was compared with a 3-year no-till rotation of winter wheat-spring barley ( Hordeum vulgare)-winter canola ( Brassica napus) and three straw management treatments: burning, straw removal, and leaving the straw stubble standing after harvest. Take-all disease and inoculum increased from years 1 to 4 in the continuous winter wheat treatment with burning and plowing, reducing plant growth compared to the no-till treatments with crop rotations. Inoculum of Rhizoctonia solani AG-8 was significantly lower in the tilled treatment compared to the no-till treatments. Inoculum concentration of Fusarium pseudograminearum was higher than that of F. culmorum, and in one of three years, the former was higher in treatments with standing stubble and mechanical straw removal compared to burned treatments. Residue management method had no effect on Rhizoctonia inoculum, but spring barley had more crown roots and tillers and greater height with stubble burning. This 6-year study showed that irrigated winter wheat can be produced in a no-till rotation without major disease losses and demonstrated how cropping practices influence the dynamics of soilborne cereal diseases and inoculum over time.
  • Authors:
    • He, X.
    • Qin, S.
    • Hu, C.
    • Zhang, Y.
    • Dong, W.
  • Source: European Journal of Soil Biology
  • Volume: 46
  • Issue: 3-4
  • Year: 2010
  • Summary: This study compared the responses of soil chemical and microbial indicators to the conservational tillage (CT) versus traditional tillage (TT) in a Haplic Cambisol in the North China Plain (NCP). These indicators included soil organic C (SOC), soil total N (STN), soil available P (SAP), cation exchange capacity (CEC), exchangeable Ca 2+ and Mg 2+, microbial biomass C (MBC), microbial biomass N (MBN), alkaline phosphomonoesterase (AP), beta-glucosidase, N-acetyl-beta-glucosaminidase (NAG), nitrate reductase (NR), protease, urease and the geometric mean of the assayed enzymes (GMea). Our results showed that almost all investigated parameters, except the contents of CEC, Ca 2+, Mg 2+ and the ratios of GMea/MBN and C/N, were significantly higher under the CT (no-till, NT and reduced-till, RT) than those under the TT, whilst the crop yield was not significantly affected by tillage treatments. Principle component analysis (PCA) showed that the first and second component explained 67.2% and 16.6% of the total variation, respectively. The first component was significantly correlated with GMea, MBC, MBN and beta-glucosidase, and effectively discriminated soils under the NT or RT from those under the TT. Our results indicated that the 6-year CT improved the quality of the Haplic Cambisol by enhancing its chemical and microbial properties, whilst GMea, MBC, MBN and beta-glucosidase were among the most effective indicators for monitoring these improvements.
  • Authors:
    • Qin, S.
    • Hu, C.
    • He, X. H.
    • Dong, W.
    • Cui, J.
    • Wang, Y.
  • Source: Applied Soil Ecology
  • Volume: 45
  • Issue: 3
  • Year: 2010
  • Summary: Micro-scale investigation is helpful for better understanding of the relationships between organic matter, microorganisms and nutrients in soil, and for better interpretation of modifications induced by soil management. The soil particle-size fractions (2000-200, 200-63, 63-2, and 2-0.1 m), contents of soil organic carbon (SOC), total N (STN), available P (SAP), dissolved organic C (DOC), light fraction organic C (LOC), microbial biomass N (MBN), basal respiration (SBR), and relevant enzyme activities of C, N and P transformations, such as beta-glucosidase (beta-G), N-acetyl-beta-glucosaminidase (N-G), protease, urease and alkaline phosphomonoesterase (APH) were analyzed to study the effects of 8-year-period conservational (no-till with residue retention) (CAM) versus traditional agricultural management (moldboard plowing without residue retention) (TAM) to a Haplic Cambisol soil in the North China Plain (NCP). Our results showed that CAM significantly enlarged the stocks of SOC, DOC, LOC, STN and SAP in the 0-10 cm layer, increased the contents of SOC, STN and SAP in the sand fractions, and promoted all of the enzyme activities in the bulk soil and all of the four particle-size fractions. Our results suggested that CAM increased the nutrient contents in the sand fractions by both enlarging the content of particulate organic matter and enhancing the activities of enzymes involved in nutrient cycling in these fractions. On the contrary, the contents of SOC and nutrients in the silt and clay fractions were relatively resistant to the conversion from CAM to TAM, indicating the limitation of CAM for stable SOC sequestration.
  • Authors:
    • Sainju, U. M.
    • Jabro, J. D.
    • Caesar-TonThat, T.
  • Source: Journal of Environmental Quality
  • Volume: 39
  • Issue: 3
  • Year: 2010
  • Summary: Management practices are needed to reduce dryland sod CO(2) emissions and to increase C sequestration We evaluated the effects of tillage and cropping sequence combinations and N fertilization on dryland crop biomass (stems + leaves) and sod surface CO(2) flux and C content (0- to 120-cm depth) in a Williams loam from May to October, 2006 to 2008, in eastern Montana. Treatments were no-tilled continuous malt barley (Hordeum vulgaris L) (NTCB), no-tilled malt bailey pea (Pivot; sativum L) (NTB-P), no-tilled malt barley fallow (NTB-F), and conventional-tilled malt barley fallow (CTB-F), each with 0 and 80 kg N ha(-1) Measurements were made both in Phase I (malt barley in NTCB, pea in NTB-P, and fallow in NTB-F and CTB-F) and Phase II (malt barley in all sequences) of each cropping sequence in every year Crop biomass varied among years. was greater in the barley than in the pea phase of the NTB-P treatment, and greater in NTCB and NTB-P than in NTB-F and CTB-F in 2 out of 3 yr Similarly biomass was greater with 80 than with 0 kg N ha(-1) in 1 out of 3 yr. Soil CO(2) flux increased from 8 mg C m(-2) h(-1) in early May to 239 mg C m(-2) h(-1) in mid-June as temperature increased and then declined to 3 mg C m(-2) h(-1) in September. October Fluxes peaked immediately following substantial precipitation (>10 mm). especially in NTCB and NTB-P Cumulative CO(2) flux from May to October was greater in 2006 and 2007 than in 2008, greater in cropping than in fallow phases, and greater in NTCB than in NTB-F. Tillage did not influence crop biomass and CO(2) flux but N fertilization had a variable effect on the flux in 2008. Similarly, soil total C content was not influenced by treatments Annual cropping increased CO(2) flux compared with crop fallow probably by increasing crop residue returns to sods and root and rhizosphere respiration Inclusion of peas in the rotation wills malt barley in the no-till system, which have been known to reduce N fertilization rates and sustain malt barley yields, resulted in a CO(2) flux similar to that in the CTB-F sequence
  • Authors:
    • Saseendran, S. A.
    • Nielsen, D. C.
    • Ma, L. W.
    • Ahuja, L. R.
    • Vigil, M. F.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 5
  • Year: 2010
  • Summary: Long-term crop rotation effects on crop water use and yield have been investigated in the Central Great Plains since the 1990s. System models are needed to synthesize these long-term results for making management decisions and for transferring localized data to other conditions. The objectives of this study were to calibrate a cropping systems model (RZWQM2 with the DSSAT v4.0 crop modules) for dryland wheat ( Triticum aestivum L.), corn ( Zea mays L.), and proso millet ( Panicum miliaceum L.) production in the wheat-corn-millet (WCM) rotation from 1995 to 2008, and then to evaluate the model from 1992-2008 for two additional rotations, wheat-fallow (WF) and wheat-corn-fallow (WCF) on a Weld silt loam soil under no-till conditions. Measured biomass and grain yield for the above three rotations were simulated reasonably well with root mean squared errors (RMSEs) ranging between 1147 and 2547 kg ha -1 for biomass, and between 280 and 618 kg ha -1 for grain yield. Corresponding index of agreement (d) ranged between 0.70 and 0.95 for biomass, and between 0.87 and 0.97 for grain yield. The validated model was further used to evaluate two additional crop rotations: wheat-millet-fallow (WMF) and wheat-corn-millet-fallow (WCMF) (1993-2008) without prior knowledge of the two rotations. We found that the model simulated the mean and range of yield and biomass of the three crops well. These results demonstrated that RZWQM2 can be used to synthesize long-term crop rotation data and to predict crop rotation effects on crop production under the semiarid conditions of eastern Colorado.