• Authors:
    • Zahoor, A.
    • Fujimaki, H.
    • Andry, H.
    • Inoue, M.
    • Uzoma, K. C.
    • Nishihara, E.
  • Source: Soil Use and Management
  • Volume: 27
  • Issue: 2
  • Year: 2011
  • Summary: In this study, we performed a greenhouse experiment to investigate the effect of cow manure biochar on maize yield, nutrient uptake and physico-chemical properties of a dryland sandy soil. Biochar was derived from dry cow manure pyrolysed at 500 degrees C. Cow manure biochar was mixed with a sandy soil at the rate equivalent to 0, 10, 15 and 20 t biochar per hectare. Maize was used as a test crop. Results of the study indicated that cow manure biochar contains some important plant nutrients which significantly affected the maize crop growth. Maize yield and nutrient uptake were significantly improved with increasing the biochar mixing rate. Application of biochar at 15 and 20 t/ha mixing rates significantly increased maize grain yield by 150 and 98% as compared with the control, respectively. Maize net water use efficiency (WUE) increased by 6, 139 and 91% as compared with the control, with the 10, 15 and 20 t/ha mixing rate, respectively. Nutrient uptake by maize grain was significantly increased with higher biochar applications. Application of cow manure biochar improved the field-saturated hydraulic conductivity of the sandy soil, as a result net WUE also increased. Results of the soil analysis after the harvesting indicated significant increase in the pH, total C, total N, Oslen-P, exchangeable cations and cation exchange capacity. The results of this study indicated that application of cow manure biochar to sandy soil is not only beneficial for crop growth but it also significantly improved the physico-chemical properties of the coarse soil.
  • Authors:
    • Holan, S. H.
    • Goyne, K. W.
    • Veum, K. S.
    • Motavalli, P. P.
  • Source: Geoderma
  • Volume: 167-168
  • Year: 2011
  • Summary: Conservation management practices including upland vegetative filter strips (VFS) and no-till cultivation have the potential to enhance soil carbon sequestration and other ecosystem services in agroecosystems. A modified two-factor analysis of variance (ANOVA) with subsamples was used to compare SOC and TN on a concentration, soil volume and soil mass basis in claypan soils planted to different conservation management practices and as a function of landscape position. The three conservation management practices (no-till cultivation, grass VFS and agroforestry VFS) and four landscape positions (summit, shoulder, backslope and footslope) investigated were compared 10 years after VFS establishment in a no-till system planted to maize ( Zea mays. L.)-soybean ( Glycine max (L.) Merr.) rotation. Two soil depth increments (0-5 cm and 5-13 cm) were modeled separately to test for treatment effects. In the surface layer, mean SOC concentration was significantly greater in the VFS soils compared to no-till. On a soil volume or mass basis, no significant differences in SOC stocks were found among treatment means. Concentration and mass based TN values were significantly greater in the grass VFS relative to no-till in the surface layer. A rapid slaking stability test, developed to separate particulate, adsorbed and occluded organic carbon (PAO-C) and nitrogen (PAO-N), showed that VFS soils had significantly greater mean PAO-C and PAO-N concentrations, soil volume and soil mass based stocks than no-till. In addition, comparison of SOC:TN and PAO-C:PAO-N ratios suggest reduced decomposition and mineralization of SOC in the PAO fraction. No significant treatment effects were detected in total or PAO soil fractions in the subsurface layer or among landscape position in either depth increment. Study results emphasize the need to compare soil carbon and nitrogen stocks on a soil volume and/or soil mass basis using bulk density measurements. Additionally, the rapid PAO separation technique was found to be a good indicator of early changes in SOC and TN in the systems studied. Overall, this research indicates that grass VFS may sequester TN more rapidly than agroforestry VFS and that a greater proportion of SOC and TN may be stabilized in VFS soils compared to no-till.
  • Authors:
    • Edwards, J.
    • Godsey, C.
    • Vitale, J. D.
    • Taylor, R.
  • Source: Journal of Soil and Water Conservation
  • Volume: 66
  • Issue: 4
  • Year: 2011
  • Summary: Conservation tillage had initial roots in the Great Plains, but the current adoption of conservation tillage, especially no-till, lags behind in the rest of the United States. This paper documents the results of a recent survey of Oklahoma producers, which was conducted to assess the current status of conservation tillage in the state. Based on responses from 1,703 producers, econometric analysis was conducted to identify factors explaining the observed use of conservation tillage practices in Oklahoma. The survey found that conventional tillage remains the most common tillage practice among Oklahoma producers. According to the survey, conventional tillage is used on 43.2% of the state's total acreage, conservation tillage on 26.7% of the total acreage, and reduced tillage on the remaining 30.1% of the crop acreage. A Tobit model was developed to explain patterns of tillage use based on producer characteristics and their perceptions on how conservation tillage performs relative to conventional tillage according to various economic and agronomic factors. The Tobit model identified operator age, farm size, crop rotation, knowledge, and erosion control as highly significant factors explaining the observed use of conservation tillage. The model results also identified potential constraints to conservation tillage adoption and use in the Southern Plains, suggesting that the unique needs of mixed crop-livestock farming systems, and the dominant winter wheat ( Triticum aestivum L.) monoculture, hinder further diffusion of conservation tillage. Future policy should consider addressing the needs of Oklahoma producers, particularly crop producers heavily engaged in livestock activities, as well as finding viable rotation crops to provide alternatives for the winter wheat monoculture.
  • Authors:
    • Hubbell, D. S.,III
    • Anders, M. M.
    • Beck, P. A.
    • Hignight, J. A.
    • Watkins, K. B.
    • Gadberry, S.
  • Source: Journal of Soil and Water Conservation
  • Volume: 66
  • Issue: 1
  • Year: 2011
  • Summary: Grazing cattle on winter wheat is a common income-generating practice in the Southern Great Plains, but few Arkansas cattle producers utilize this practice. Many areas in the state with potential to benefit from this practice are highly erodible, and conservation tillage may be needed to best ensure the existing natural resource base is not degraded over time. This study evaluates the profitability and return variability of grazing stocker steers on conservation tillage winter wheat pasture using simulation and stochastic dominance analysis. Average daily gains are simulated for steers grazed on conventional tillage, reduced tillage, and no-till winter wheat pasture using seven years of steer weight gain data from a conservation tillage winter wheat forage study near Batesville, Arkansas. Steer prices and prices for key forage production inputs such as diesel, fertilizer, and glyphosate are also simulated to account for their stochastic impacts on return variability. Steer net return distributions are generated for each tillage system, and first and second degree stochastic dominance are used to rank each tillage system according to specified producer preferences. The results indicate both conservation tillage systems are more profitable and less risky than the conventional tillage system. The conventional tillage system is dominated by no-till based on first degree stochastic dominance and by reduced tillage based on second degree stochastic dominance. Thus both conservation tillage systems would be preferred by risk-averse cattle producers to the conventional tillage system based on this analysis.
  • Authors:
    • Torbert, H. A.
    • Watts, D. B.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: Reduced tillage, poultry litter applications, crop rotations, and winter cover cropping are management practices that could be used with conservation tillage systems to increase yields compared to conventional monoculture systems. This study evaluated cropping sequences of corn ( Zea mays L.), soybean [ Glycine max (L.) Merr.], and corn-soybean rotations with wheat ( Triticum aestivum L.) covers in conventional, strip, and no-tillage (no-till) systems, following poultry litter additions to wheat cover. The study was conducted from 1991 to 2001 on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Poultry litter (112 kg N ha -1) was applied to wheat each year in fall. Wheat not receiving poultry litter received equivalent inorganic N. Corn was fertilized with inorganic fertilizer in spring with 56 kg N ha -1 at planting followed by 168 kg N ha -1 3 wk after emergence; soybean received no fertilizer. Corn yields were influenced by tillage in 1991, 1992, 1993, 1994, 1996, 1997, 1998, and 2001 with conventional tillage producing greater yields, except in 1993 (strip tillage) and 2001 (no-till). Poultry litter increased corn yield in 1991, 1997, and 1998. Crop rotations increased corn yield for all years, except 2001. Soybean yields were not impacted by differences in tillage. Crop rotations significantly impacted soybean yield in 1992, 1995, and 1998, with higher yields observed in 1992, and 1995, and lower yields in 1998. Poultry litter significantly increased soybean yield 8 of the 9 yr evaluated. This study suggests that poultry litter use for these crop rotations in conservation tillage systems could increase sustainable yield production.
  • Authors:
    • Wells, M. L.
  • Source: HortScience
  • Volume: 46
  • Issue: 9
  • Year: 2011
  • Summary: Nitrogen (N) fertilizer application to plants at rates not adjusted for the N contribution from soil N availability may result in overapplication of fertilizer. Further understanding of proper timing of N applications based on soil N dynamics and plant demand can be valuable information for the efficient use of fertilizer N. The present study measures soil N dynamics in a pecan orchard under various N fertilizer regimes on a southeastern U.S. Coastal Plain soil. The following treatments were evaluated: 1) crimson clover (Trifolium incarnatum L.); 2) poultry litter; 3) crimson clover + poultry litter; 4) ammonium nitrate (NH(4)NO(3)); and 5) untreated control. Crimson clover provided from 20 to 75 kg.ha(-1) N over the course of the two growing seasons; however, most of the available N from crimson clover became available late in the growing season. As a result, supplemental N may be required in spring where crimson clover is used as an orchard cover crop. Poultry litter, with and without clover, provided available N consistently throughout the growing season with more N becoming available later in the season than earlier. This suggests that poultry litter applications for pecan should be timed before budbreak. Under optimum environmental conditions, N from NH(4)NO(3) is most available within the first 30 days of application. Thus, it appears that synthetic fertilizer applications using NH(4)NO(3) as the N source should be targeted at or 2 to 3 weeks after pecan budbreak.
  • Authors:
    • White, C. M.
    • Weil, R. R.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 1
  • Year: 2011
  • Summary: Cover crops can influence nutrient cycling in the agroecosystem. Forage radish (FR) (Raphanus sativus L. var. longipinnatus) is unique in terms of P cycling because of its high tissue P concentration, rapid growth in the fall, and rapid decomposition in winter and spring. In addition, FR produces a taproot that decays during the winter and leaves distinct holes in the surface soil. This study measured P uptake by FR and cereal rye (CR) (Secale cereale L.) cover crops; the Mehlich 3 P concentration (M3P) in bulk soil following FR, CR, and no cover crop (NC); and M3P in soil within 3 cm of FR taproot holes. Cover crop treatments of FR, CR, and NC were established at two sites each fall for three subsequent years in a cover crop-corn (Zea mays L.) silage rotation. Cover crop shoot P uptake ranged from 5.9 to 25 kg P ha(-1) for FR measured in the fall and from 3.0 to 26 kg P ha(-1) for CR measured in the spring. The greatest cover crop effect on bulk soil M3P was observed at the 0- to 2.5-cm depth aft er 3 yr of cover crops, with M3P values of 101, 82, and 79 mg P kg(-1) aft er FR, CR, and NC, respectively. Soil within 3 cm of FR taproot holes had greater M3P than FR and NC bulk soil. Further studies should be conducted to determine if FR could increase P removal rates in excessively high P soils or increase P availability in low P soils.
  • Authors:
    • Chen, G. H.
    • Khalilian, A.
    • Wiatrak, P.
  • Source: American Journal of Agricultural and Biological Sciences
  • Volume: 6
  • Issue: 1
  • Year: 2011
  • Summary: Problem statement: Insufficient rainfall under low yield environment may affect nitrogen management, plant growth indices and grain yields of corn ( Zea mays L.). Approach: The objective of this study was to determine the effects of two N application timings (all at planting and as split application with N applied at planting and V6 stage) and five N fertilizer rates (0, 45, 90, 135 and 180 kg N ha -1) on strip-tilled, dryland corn growth and yields under low-yield environmental conditions near Blackville SC, from 2007-2009. Plant growth measurements included plant height, ear height, relative chlorophyll content (SPAD), Leaf Area Index (LAI) and normalized difference vegetation index (NDVI). Results: Plant LAI at V8, NDVI at V8 and R1, SPAD at R1, plant height at V8 and grain yield generally increased with increasing N application rates. Due to most likely insufficient precipitation, the N application timing did not affect corn growth or yield. Despite relatively low grain yields, corn yield was increased by 1.6 Mg ha -1 with increasing N application rate of 100 kg ha -1. Grain yield was positively correlated with plant leaf area index (LAI) at R1 (r=0.27, p≤0.05) and Normalized Difference Vegetation Index (NDVI) at V8 and R1 (r=0.33 and 0.29, p≤0.01, respectively) and plant height at V8 stage (r=0.42, p≤0.001). With N applied at planting, there was a 0.55 and 0.49 Mg ha -1 yield increase with 0.1 increases in plant NDVI at V8 and R1, respectively. Conclusion: Under strip tillage and low yield environment conditions, plant growth and yields may not be affected by timing of N application mainly due to insufficient rainfall. Plant NDVI (for treatments with all N applied at planting) at V8 and R1 can help to estimate potential of corn grain yield, which may be reduced due to low nitrogen use efficiency.
  • Authors:
    • Holmes, P.
    • Wiggs, G.
  • Source: Earth Surface Processes and Landforms
  • Volume: 36
  • Issue: 6
  • Year: 2011
  • Summary: The west-central part of South Africa's Free State Province falls within the transition zone between South Africa's sub-humid, temperate grasslands to the east, and the semi-arid Karoo and arid Kalahari to the south and west, respectively. The area is characterized by low rainfall (typically 500 mm or less) with high variability, but environmental conditions allow widespread dryland commercial agriculture (maize, sunflowers and stock farming). However, human activity promotes wind erosion and the area is susceptible to dust emissions. This study is the first to quantify the degree of wind erosion on the agricultural soils in the region under prevailing winter to spring climatic conditions and land management practices. Using arrays of cup anemometers, dust deposition traps and saltation impact sensors (Safires), measurements were made of the key erosivity and erodibility drivers that control the degree of wind erosion. Results demonstrate that significant quantities of dust are mobilized, particularly during the months of September and October. Thresholds of wind erosion are shown to respond particularly closely to changes in surface and aerodynamic roughness ( z0) with the amount of collected dust correlating well with measures of wind erosivity that weight the impact of higher wind speeds. Given the importance of surface roughness in controlling erosion thresholds, results show that the opportunity exists for well designed farming practices to control wind erosion. However, it is likely that climatically driven environmental change will impact on some of the identified controls on erosion (wind power, moisture availability) with the result that the wind erosion hazard is likely to increase within this marginal environment.
  • Authors:
    • Li, H.
    • Cheng, J.
    • Zhang, J.
    • Yue, T.
    • Xi, Z.
  • Source: Scientia Agricultura Sinica
  • Volume: 44
  • Issue: 11
  • Year: 2011
  • Summary: Objective: In this paper, the relationship between soil quality and soil biological characteristics such as soil microorganism quantity and soil enzymatic activity was studied in the intercropping system of vineyard, in order to illustrate the function of soil biological characteristics as bio-indicators of soil fertility. Method: Three such cover crops, two perennial legumes (white clover and alfalfa) and a perennial gramineous grass (tall fescue) were sown in vineyard. Soil microorganism quantity, soil enzymatic activities and soil nutrient content were analyzed and compared with that in soil cultivation. [Result] Most detected soil microorganism quantity and soil enzymatic activity, soil organic matter were increased under cover crop treatments, compared to clean tillage, tall fescue treatment decreased urease and sucrase activity. White clover and alfalfa treatments significantly increased the contents of hydrolyzable N, total N and available K, and tall fescue decreased them, while the activated organic P in tall fescue treatment was more effectively than that in white clover and alfalfa treatments. Correlation analysis indicated that soil organic matter, total N, hydrolyzable N, total P, available K showed significant or very significant positive correlation with 10 soil biological characteristic factors such as bacteria, fungi, actinomyces, azotobacter, cellulose-decomposing bacteria, urease, phosphatase, amylase, sucrase, and cellulose. The catalase activity was no significant correlation with all the soil nutrient contents, and the total K content was no significant correlations with all the soil biological characteristic factors. The soil pH in this experiment was negatively correlated with soil biological properties. Conclusion: Cover crops in the inter-rows of vineyard increased soil microorganism quantity, soil enzymatic activity and soil nutrient content, white clover and alfalfa treatments were better than tall fescue. There are significant correlations between soil biological characteristics and nutrients, and soil biological indexes could reflect the changes of soil quality.