• Authors:
    • Raman, A.
    • Ladha, J. K.
    • Kumar, V.
    • Sharma, S.
    • Piepho, H. P.
  • Source: Field Crops Research
  • Volume: 121
  • Issue: 3
  • Year: 2011
  • Summary: Normally, the data generated from farmer participatory trials (FPT) are highly unbalanced due to variation in the number of replicates of different treatments, the use of different varieties, farmers’ management of the trials, and their preferences for testing different treatments. The incomplete nature of the data makes mixed models the preferred class of models for the analysis. When assessing the relative performances of technologies, stability over a range of environments is an important attribute to consider. Most of the common models for stability may be fitted in a mixed-model framework where environments are a random factor and treatments are fixed. Data from on-farm trials conducted in the Indo-Gangetic Plain (IGP) of South Asia under the umbrella of Rice–Wheat Consortium (RWC) were analyzed for grain yield stability using different stability models. The objective was to compare improved resource management technologies with farmers’ practice. The variance components of an appropriate mixed model serve as measures of stability. Stability models were compared allowing for (i) heterogeneity of error variances and (ii) heterogeneity of variances between environments for farmers-within-environment effects. Mean comparisons of the treatments were made on the basis of the best fitting stability model. Reduced-till (non-puddled) transplanted rice (RT-TPR) and reduced-till drill-seeded wheat using a power tiller – operated seeder with integrated crop and resource management RTDSW(PTOS)ICRM ranked first in terms of both adjusted mean yield and stability.
  • Authors:
    • Blanco-Canqui, H.
    • Mikha, M. M.
    • Presley, D. R.
    • Claassen, M. M.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Inclusion of cover crops (CCs) may be a potential strategy to boost no-till performance by improving soil physical properties. To assess this potential, we utilized a winter wheat ( Triticum aestivum L.)-grain sorghum [ Sorghum bicolor (L.) Moench] rotation, four N rates, and a hairy vetch (HV; Vicia villosa Roth) CC after wheat during the first rotation cycles, which was replaced in subsequent cycles with sunn hemp (SH; Crotalaria juncea L.) and late-maturing soybean [LMS; Glycine max (L.) Merr.] CCs in no-till on a silt loam. At the end of 15 yr, we studied the cumulative impacts of CCs on soil physical properties and assessed relationships between soil properties and soil organic C (SOC) concentration. Across N rates, SH reduced near-surface bulk density (rho b) by 4% and increased cumulative infiltration by three times relative to no-CC plots. Without N application, SH and LMS reduced Proctor maximum rho b, a parameter of soil compactibility, by 5%, indicating that soils under CCs may be less susceptible to compaction. Cover crops also increased mean weight diameter of aggregates (MWDA) by 80% in the 0- to 7.5-cm depth. The SOC concentration was 30% greater for SH and 20% greater for LMS than for no-CC plots in the 0- to 7.5-cm depth. The CC-induced increase in SOC concentration was negatively correlated with Proctor maximum rho b and positively with MWDA and cumulative infiltration. Overall, addition of CCs to no-till systems improved soil physical properties, and the CC-induced change in SOC concentration was correlated with soil physical properties.
  • Authors:
    • Brar, A. S.
    • Mahal, S. S.
    • Buttar, G. S.
    • Deol, J. S.
  • Source: Indian Journal of Agronomy
  • Volume: 56
  • Issue: 4
  • Year: 2011
  • Summary: A field experiment was conducted to work out the water productivity, economics and energetics of basmati rice ( Oryza sativa L.)-wheat [ Triticum aestivum (L.) emend. Fiori & Paol] sequence under different methods of crop establishment during 2005-06 and 2006-07. The treatments included combinations of two crop establishment methods of basmati rice (direct seeded and transplanted) and three seeding techniques of succeeding wheat (conventional, bed planting and zero tillage). Productivity of basmati rice-wheat sequence was significantly higher with transplanted basmati rice (TPBR) than direct seeded basmati rice (DSBR) irrespective of seeding technique of succeeding wheat. However, crop establishment methods of wheat did not show any significant impact on total productivity of basmati rice-wheat sequence during both the years. Total water use was 9.5 and 8.2 per cent higher in TPBR-wheat sequence than DSBR-wheat sequence during 2005-06 and 2006-07, respectively. In this sequence the highest net return was obtained from TPBR-zero till sown wheat sequence, which was closely followed by TPBR-conventionally sown wheat sequence but both gave more net returns than DSBR-zero till sown wheat sequence. The highest energy output was recorded in TPBR-conventionally sown wheat, while energy use efficiency was maximum in TPBR-zero till sown wheat, during both the years because of lowest energy input in zero till sown wheat than conventional and bed planting.
  • Authors:
    • ZhiKuan, J.
    • Lei, M.
    • FangQian, G.
    • BaoPing, Y.
    • YaoWei, H.
    • XiaoLong, R.
    • TaiYi, C.
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 27
  • Issue: 3
  • Year: 2011
  • Summary: A field experiment (2008-2009) was conducted at the Heyang Dryland Farming Experimental Station in Shaanxi Province of China to determine the effects of straw mulch rates on soil moisture and spring maize ( Zea mays L.) yield. Maize straw at rates of 0 (CK), 4 500, 9 000 and 13 500 kg/hm 2 was placed on field plots. The results indicated that the average soil water storage in the 0-200 cm soil layers under the three different rates of straw mulch were 16.52, 25.52 and 34.04 mm, respectively, significantly ( P<0.05) higher than that of CK, and the average field evapotranspiration (ET) in the 0-200 cm soil layers were 4.43, 8.23 and 6.96 mm, respectively, significantly ( P<0.05) lower than that of CK during 0-60 days after sowing. Besides, the average grain yield and water use efficiency (WUE) of the treatment with 9 000 kg/hm 2 of straw mulch were optimal among the treatments, its grain yield and WUE increased by 11.03% ( P<0.05) and 9.25% ( P<0.05) compared with the CK, while it was medium with the treatment of 13 000 kg/hm 2, and lowest with the treatment with 4 500 kg/hm 2. It is suggested that the treatment with 9 000 kg/hm 2 of straw mulch is preferable for Weibei highland area in China, as the precipitation is below than 390 mm during the maize growing season.
  • Authors:
    • Caires, E. F.
    • Garbuio, F. J.
    • Churka, S.
    • Joris, H. A. W.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 6
  • Year: 2011
  • Summary: Gypsum has been used in tropical and subtropical agriculture when subsoil acidity is an important yield-limiting factor. However, the conditions that promote increased crop yield as a result of gypsum addition in no-till (NT) systems still remain unclear. A field trial examined the effects of newly and previously surface-applied gypsum in a long-term NT system on the soil chemical properties and nutrition and yield of corn ( Zea mays L.), wheat ( Triticum aestivum L.), and soybean [ Glycine max (L.) Merr.] on a clayey Rhodic Hapludox in Parana State, Brazil. Gypsum was surface-applied at 0 and 6 Mg ha -1 in 2004 on plots that had received gypsum previously at 0, 3, 6, and 9 Mg ha -1 in 1998. Surface-applied gypsum newly and previously improved exchangeable Ca and SO 4-S availability throughout the soil profile, and increased the cumulative grain yield of the crops. Exchangeable K losses through leaching caused by gypsum application were low, and a larger mobility of exchangeable Mg as compared with exchangeable K in soil was found as a result of gypsum addition. An increase in Ca content in the corn, wheat, and soybean leaves, and in S content in the corn and wheat leaves occurred following the gypsum application. The use of gypsum showed economic viability to maximize crop grain production in a long-term NT soil with a sufficient level of exchangeable Ca (≥8 mmol c dm -3) and low levels of exchangeable Al (≤4 mmol c dm -3) and Al saturation (≤15%) in the subsoil layers (20-60 cm).
  • Authors:
    • Chamberlain, J. F.
    • Miller, S. A.
    • Frederick, J. R.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 141
  • Issue: 3-4
  • Year: 2011
  • Summary: Use of a simulation model to predict long-term yield, greenhouse gas (GHG) emissions, and water quality impacts can be valuable for assessing land use conversion to bioenergy crops. The objective of this study is to assess the usability of DAYCENT for measuring environmental impacts due to land conversions from cotton and CRP lands (as unmanaged grasses) to switchgrass in the Southern U.S. We use published yield data to calibrate the crop growth parameters and test the calibrated model on independent data sets. We then apply the model to predict other relevant C and N parameters. In the case of cotton, the model simulates long-term mean cotton lint yield within 25% of observed yields across the South and within 4% of yields in the case study area of Darlington County, SC. DAYCENT also matches observed mature switchgrass yields within 25% of the mean in the range of expected fertilization rates across the region and within 6% in the case study area. Long-term simulations predict a decrease in GHG emissions (1.0-3.8 MtCO 2-e/ha-yr) and a reduction of nitrate runoff (up to 95%) for conversions from cotton to switchgrass at N application rates of 0-135 kgN/ha. Conversely, conversion from unmanaged grasses to switchgrass resulted in annual increases of net GHG emissions (0.2-1.4 MtCO 2-e/ha-yr) for switchgrass at no and low (45 kgN/ha) fertilization rates. Sequestration occurs due to increased soil organic C when higher levels of N are applied. At all levels of fertilization, a reduction of nitrate (50-70%) occurs when converting from unmanaged, unharvested grasses. The amount of nitrate leaching is only slightly sensitive to the fertilization rate applied to the perennial switchgrass. DAYCENT sufficiently models the "carbon debt" from land use conversion from CRP grasslands to managed switchgrass and highlights the importance of fertilization rate. Both C and N parameter results fall within published observed ranges. Thus, the long-term (10-15-year) accuracy of the model for both cotton and switchgrass offers promise as a tool for analyzing land use conversions in terms of N-managed yields and subsequent environmental impacts and benefits.
  • Authors:
    • Chen, G.
    • Weil, R. R.
  • Source: Soil & Tillage Research
  • Volume: 117
  • Year: 2011
  • Summary: The yield of rainfed crops is commonly limited by the availability of soil water during the summer growing season. Channels produced by cover crop roots in fall/winter when soils are relatively moist may facilitate the penetration of compacted soils by subsequent crop roots in summer when soils are relatively dry and hard. Our objective was to determine the effects of fall cover crops on maize (Zea mays) growth and soil water status under three levels (high, medium, and no) of imposed traffic compaction. The study was conducted on coastal plain soils (fine-loamy Typic/Aquic hapludults and siliceous, Psammentic hapludults) in the mid-Atlantic region of the United States from 2006 to 2008. Cover crop treatments were FR (forage radish: Raphanus sativus var. longipinnatus, cv. 'Daikon'), rapeseed (Brassica napus, cv. 'Essex'), rye (cereal rye: Secale cereale L, cv. 'Wheeler') and NCC (no cover crop). Maize under high compaction achieved more deep-roots following FR and rapeseed than following rye or NCC. However, maize had greater yield following all cover crops than NCC control regardless of compaction levels and soil texture. Compaction reduced maize yield only under the high compaction in the lightly textured soils. During 24 June-24 July 2008, soils at 15 and 50 cm depths were drier under no compaction than high compaction and drier following FR than other cover crop treatments. Our results suggest that FR benefited maize root penetration in compacted soils while rye provided the best availability of surface soil water; rapeseed tended to provide both benefits. However, as rapeseed is relatively difficult to kill in spring, a mixture of FR and rye cover crops might be most practical and beneficial for rainfed summer crops under no-till systems in regions with cool to temperate, humid climates.
  • Authors:
    • Cheng, L.
    • Booker, F. L.
    • Burkey, K. O.
    • Tu, C.
    • Shew, H. D.
    • Rufty, T. W.
    • Fiscus, E. L.
    • Deforest, J. L.
    • Hu, S. J.
  • Source: PLOS ONE
  • Volume: 6
  • Issue: 6
  • Year: 2011
  • Summary: Climate change factors such as elevated atmospheric carbon dioxide (CO 2) and ozone (O 3) can exert significant impacts on soil microbes and the ecosystem level processes they mediate. However, the underlying mechanisms by which soil microbes respond to these environmental changes remain poorly understood. The prevailing hypothesis, which states that CO 2- or O 3-induced changes in carbon (C) availability dominate microbial responses, is primarily based on results from nitrogen (N)-limiting forests and grasslands. It remains largely unexplored how soil microbes respond to elevated CO 2 and O 3 in N-rich or N-aggrading systems, which severely hinders our ability to predict the long-term soil C dynamics in agroecosystems. Using a long-term field study conducted in a no-till wheat-soybean rotation system with open-top chambers, we showed that elevated CO 2 but not O 3 had a potent influence on soil microbes. Elevated CO 2 (1.5 * ambient) significantly increased, while O 3 (1.4 * ambient) reduced, aboveground (and presumably belowground) plant residue C and N inputs to soil. However, only elevated CO 2 significantly affected soil microbial biomass, activities (namely heterotrophic respiration) and community composition. The enhancement of microbial biomass and activities by elevated CO 2 largely occurred in the third and fourth years of the experiment and coincided with increased soil N availability, likely due to CO 2-stimulation of symbiotic N 2 fixation in soybean. Fungal biomass and the fungi:bacteria ratio decreased under both ambient and elevated CO 2 by the third year and also coincided with increased soil N availability; but they were significantly higher under elevated than ambient CO 2. These results suggest that more attention should be directed towards assessing the impact of N availability on microbial activities and decomposition in projections of soil organic C balance in N-rich systems under future CO 2 scenarios.
  • Authors:
    • Costa, M. S. S. de M.
    • Pivetta, L. A.
    • Steiner, F.
    • Costa, L. A. de M.
    • Castoldi, G.
    • Gobbi, F. C.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 6
  • Issue: 4
  • Year: 2011
  • Summary: Crop systems and fertilization sources can affect the chemical properties of the soil and, consequently, its fertility. With the aim of evaluating the effect of such management practices, soil samples collected at 0.0-0.10; 0.10-0.20; and 0.20-0.40 m in depth were collected and analyzed in the second year of an experiment installed in 2006 in a Rhodic Hapludox under no-till farming, located in the Agronomic Experimental Station of UNIOESTE, in the city of Marechal Candido Rondon, Parana, Brazil. The experiment consisted of two crop systems (with and without rotation of cover crops) and three fertilization sources (mineral, organic and mineral+organic). The organic and mineral+organic fertilizations consisted of the application of animal manure alone and animal manure mixed with mineral fertilizer, respectively. The values of pH, exchangeable potassium (K +) and cation exchange capacity (CEC) were not affected by the different crop systems, related to the application of different fertilization sources. However, they did influence the organic matter contents (OM), potential acidity (H ++Al 3+), exchangeable aluminum (Al 3+), phosphorus (P), calcium (Ca 2+), magnesium (Mg 2+), and the bases sum and saturation (V%). The organic and mineral+organic fertilizations, with animal manure promoted the highest increase in soil Ca and Mg.
  • Authors:
    • Crusciol, C. A. C.
    • Garcia, . A.
    • Castro, G. S. A.
    • Rosolem, C. A.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: Especially under no-tillage, subsuface soil acidity has been a problem, because it depends on base leaching, which has been associated with the presence of low molecular weigth organic acids and companion anions. The objective of this study was to evaluate exchangeable base cation leaching as affected by surface liming along with annual urea side-dressing of maize and upland rice. Treatments consisted of four lime rates (0, 1500, 3000, and 6000 kg ha -1) combined with four nitrogen rates (0, 50, 100, and 150 kg ha -1) applied to maize ( Zea mays) and upland rice ( Oryza sativa), in two consecutive years. Maize was planted in December, three months after liming. In September of the following year, pearl millet ( Pennisetum glaucum) was planted without fertilization and desiccated 86 days after plant emergence. Afterwards, upland rice was grown. Immediately after upland rice harvest, 18 months after surface liming, pH and N-NO 3-, N-NH 4+, K, Ca, and Mg levels were evaluated in soil samples taken from the layers 0-5, 5-10, 10-20 and 20-40 cm. Higher maize yields were obtained at higher N rates and 3000 kg ha -1lime. Better results for upland rice and pearl millet yields were also obtained with this lime rate, irrespective of N levels. The vertical mobility of K, Ca and Mg was higher in the soil profiles with N fertilization. Surface liming increased pH in the upper soil layers causing intense nitrate production, which was leached along with the base cations.