• Authors:
    • Benjamin, J. G.
    • Nielsen, D. C.
    • Vigil, M. F.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 2
  • Year: 2011
  • Summary: No-till dryland winter wheat ( Triticum aestivum L.)-fallow systems in the central Great Plains have more water available for crop production than the traditional conventionally tilled winter wheat-fallow systems because of greater precipitation storage efficiency. That additional water is used most efficiently when a crop is present to transpire the water, and crop yields respond positively to increases in available soil water. The objective of this study was to evaluate yield, water use efficiency (WUE), precipitation use efficiency (PUE), and net returns of cropping systems where crop choice was based on established crop responses to water use while incorporating a grass/broadleaf rotation. Available soil water at planting was measured at several decision points each year and combined with three levels of expected growing season precipitation (70, 100, 130% of average) to provide input data for water use/yield production functions for seven grain crops and three forage crops. The predicted yields from those production functions were compared against established yield thresholds for each crop, and crops were retained for further consideration if the threshold yield was exceeded. Crop choice was then narrowed by following a rule which rotated summer crops (crops planted in the spring with most of their growth occurring during summer months) with winter crops (crops planted in the fall with most of their growth occurring during the next spring) and also rotating grasses with broadleaf crops. Yields, WUE, PUE, value-basis precipitation use efficiency ($PUE), gross receipts, and net returns from the four opportunity cropping (OC) selection schemes were compared with the same quantities from four set rotations [wheat-fallow (conventional till), (WF (CT)); wheat-fallow (no-till), (WF (NT)); wheat-corn ( Zea mays L.)-fallow (no-till), (WCF); wheat-millet ( Panicum miliaceum L.) (no-till), (WM)]. Water use efficiency was greater for three of the OC selection schemes than for any of the four set rotations. Precipitation was used more efficiently using two of the OC selection schemes than using any of the four set rotations. Of the four OC cropping decision methods, net returns were greatest for the method that assumed average growing season precipitation and allowed selection from all possible crop choices. The net returns from this system were not different from net returns from WF (CT) and WF (NT). Cropping frequency can be effectively increased in dryland cropping systems by use of crop selection rules based on water use/yield production functions, measured available soil water, and expected precipitation.
  • Authors:
    • Pinto, C.
    • Sizenando Filho, F.
    • Cysne, J.
    • Pitombeira, J.
  • Source: Revista Verde de Agroecologia e Desenvolvimento Sustentavel
  • Volume: 6
  • Issue: 2
  • Year: 2011
  • Summary: Field experiments were conducted in Ceara, Brazil, to study the response of castor bean intercropping with sesame, cotton, maize and cowpea under dryland conditions. The intercropping indices evaluated were LER, LEC, ATER, mean of LER and ATER, SPI, CoR, RCC, CR, A and ALY. Castor beans and intercrops had reductions in yield. Based on the LER, LEC, CRA, AYL and CoR in the intercropping systems, the castor bean + maize treatment was the most advantageous under dryland farming. Based on the A and ALY indices, castor bean was dominated by sesame, cotton, maize and cowpea. The castor bean, cotton, sesame and castor bean, castor bean, maize treatments showed yield stability, which was characterized by the productivity index of the system (SPI).
  • Authors:
    • Preez, C.
    • Huyssteen, C.
    • Mnkeni, P.
  • Source: South African Journal of Science
  • Volume: 107
  • Issue: 5/6
  • Year: 2011
  • Summary: The decline of soil organic matter as a result of agricultural land use was identified for a review with the ultimate aim of developing a soil protection strategy and policy for South Africa. Such a policy is important because organic matter, especially the humus fraction, influences the characteristics of soil disproportionately to the quantities thereof present. Part 1 of this review dealt with the spatial variability of soil organic matter and the impact of grazing and burning under rangeland stock production. In this second part of the review, the impact of arable crop production on soil organic matter is addressed. A greater number of studies have addressed the degradation of soil organic matter that is associated with arable crop production than the restoration. However, cropping under dryland has been found to result in significant losses of soil organic matter, which is not always the case with cropping under irrigation. Restoration of soil organic matter has been very slow upon the introduction of conservational practices like zero tillage, minimal tillage, or mulch tillage. Reversion of cropland to perennial pasture has also been found to result in discouragingly slow soil organic matter restoration. Although increases or decreases in soil organic matter levels have occurred in the upper 300 mm, in most instances this took place only in the upper 50 mm. The extent of these changes was dependent inter alia on land use, soil form and environmental conditions. Loss of soil organic matter has resulted in lower nitrogen and sulphur reserves, but not necessarily lower phosphorus reserves. Depletion of soil organic matter coincided with changes in the composition of amino sugars, amino acids and lignin. It also resulted in a decline of water stable aggregates which are essential in the prevention of soil erosion. Although much is known about how arable crop production affects changes in soil organic matter, there are still uncertainties about the best management practices to maintain and even restore organic matter in degraded cropland. Coordinated long-term trials on carefully selected ecotopes across the country are therefore recommended to investigate cultivation practices suitable for this purpose.
  • Authors:
    • Jabro, J. D.
    • Lartey, R. T.
    • Evans, R. G.
    • Allen, B. L.
    • Sainju, U. M.
    • Lenssen, A. W.
    • Caesar-TonThat, T.
  • Source: Plant and Soil
  • Volume: 338
  • Issue: 1-2
  • Year: 2011
  • Summary: Novel management practices are needed to increase dryland soil organic matter and crop yields that have been declining due to long-term conventional tillage with spring wheat ( Triticum aestivum L.)-fallow system in the northern Great Plains, USA. The effects of tillage, crop rotation, and cultural practice were evaluated on dryland crop biomass (stems+leaves) yield, surface residue, and soil organic C (SOC) and total N (STN) at the 0-20 cm depth in a Williams loam (fine-loamy, mixed, superactive, frigid, Typic Argiustolls) from 2004 to 2007 in eastern Montana, USA. Treatments were two tillage practices [no-tillage (NT) and conventional tillage (CT)], four crop rotations [continuous spring wheat (CW), spring wheat-pea ( Pisum sativum L.) (W-P), spring wheat-barley ( Hordeum vulgaris L.) hay-pea (W-B-P), and spring wheat-barley hay-corn ( Zea mays L.)-pea (W-B-C-P)], and two cultural practices [regular (conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height) and ecological (variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height)]. Crop biomass and N content were 4 to 44% greater in W-B-C-P than in CW in 2004 and 2005 and greater in ecological than in regular cultural practice in CT. Soil surface residue amount and C and N contents were greater in NT than in CT, greater in CW, W-P, and W-B-C-P than in W-B-P, and greater in 2006 and 2007 than in 2004 and 2005. The SOC and STN concentrations at 0-5 cm were 4 to 6% greater in CW than in W-P or W-B-P in NT and CT from 2005 and 2007. In 2007, SOC content at 10-20 cm was greater in W-P and W-B-P than in W-B-C-P in CT but STN was greater in W-B-P and W-B-C-P than in CW in NT. From 2004 to 2007, SOC and STN concentrations varied at 0-5 cm but increased at 5-20 cm. Diversified crop rotation and delayed planting with higher seed rates and banded N fertilization increased the amount of crop biomass returned to the soil and surface residue C and N. Although no-tillage increased surface residue C and N, continuous nonlegume cropping increased soil C and N levels at the surface layer compared with other crop rotations. Continued return of crop residue from 2004 to 2007 may increase soil C and N levels but long-term studies are needed to better evaluate the effect of management practices on soil C and N levels under dryland cropping systems in the northern Great Plains.
  • Authors:
    • Singh, R.
    • Sharma, A. R.
    • Dhyani, S. K.
    • Dube, R. K.
  • Source: Journal of Crop Improvement
  • Volume: 25
  • Issue: 4
  • Year: 2011
  • Summary: Mulching is highly beneficial for resource conservation under rainfed conditions, but non-availability of organic biomass and easy availability of fertilizers and herbicides has led to a gradual discontinuation of this practice. Various vegetative materials, including some troublesome weedy perennials, are available locally, which can be recycled for enhanced soil moisture and nutrient conservation. A field experiment was conducted at Dehradun, India, from 2001-2004 to study the effect of mulching with kudzu ( Peuraria hirsuta), wild sage ( Lantana camara), and subabul ( Leucaena leucocephala) applied at 30 and 60 days of growth of maize ( Zea mays), maize harvest, and sowing of wheat ( Triticum aestivum). Application of 10 t/ha (fresh biomass) added 1.6-2.3 t dry matter through Peuraria, 2.5-3-2 t through Lantana, and 2.9-3-9 t/ha through Leuceana, which contributed 47.7-60.9 kg N, 58.4-70.9 kg N, and 118.4-148.4 kg N/ha, respectively. All mulching materials were beneficial and improved productivity of maize significantly by 16.6-20.6% over no mulching. Wheat yield also increased because of mulching in previous maize (+11.2%), and the beneficial effect was relatively greater (12.4-25.1%) when mulching was done at maize harvest or wheat sowing. Mulching showed improvement in organic C and total N status, and a decrease in bulk density associated with an increase in infiltration rate across three cropping cycles. Wheat gave three to five times more net profit than maize, and the net benefit-cost ratio of the system was the highest (1.34-1.35) when mulching was done at 60 days of maize growth with Peuraria and Leucaena. It was concluded that mulching with available vegetative materials in standing crop of maize or after harvest was beneficial for improving moisture conservation, productivity, and profitability of a maize-wheat cropping system under Doon valley conditions.
  • Authors:
    • Shah, Z.
    • Stromberger, M. E.
    • Westfall, D. G.
  • Source: Soil Biology and Biochemistry
  • Volume: 43
  • Issue: 1
  • Year: 2011
  • Summary: The need to identify microbial community parameters that predict microbial activity is becoming more urgent, due to the desire to manage microbial communities for ecosystem services as well as the desire to incorporate microbial community parameters within ecosystem models. In dryland agroecosystems, microbial biomass C (MBC) can be increased by adopting alternative management strategies that increase crop residue retention, nutrient reserves, improve soil structure and result in greater water retention. Changes in MBC could subsequently affect microbial activities related to decomposition, C stabilization and sequestration. We hypothesized that MBC and potential microbial activities that broadly relate to decomposition (basal and substrate-induced respiration, N mineralization, and beta-glucosidase and arylsulfatase enzyme activities) would be similarly affected by no-till, dryland winter wheat rotations distributed along a potential evapotranspiration (PET) gradient in eastern Colorado. Microbial biomass was smaller in March 2004 than in November 2003 (417 vs. 231 g g -1 soil), and consistently smaller in soils from the high PET soil (191 g g -1) than in the medium and low PET soils (379 and 398 g g -1, respectively). Among treatments, MBC was largest under perennial grass (398 g g -1). Potential microbial activities did not consistently follow the same trends as MBC, and the only activities significantly correlated with MBC were beta-glucosidase ( r=0.61) and substrate-induced respiration ( r=0.27). In contrast to MBC, specific microbial activities (expressed on a per MBC basis) were greatest in the high PET soils. Specific but not total activities were correlated with microbial community structure, which was determined in a previous study. High specific activity in low biomass, high PET soils may be due to higher microbial maintenance requirements, as well as to the unique microbial community structure (lower bacterial-to-fungal fatty acid ratio and lower 17:0 cy-to-16:1omega7c stress ratio) associated with these soils. In conclusion, microbial biomass should not be utilized as the sole predictor of microbial activity when comparing soils with different community structures and levels of physiological stress, due to the influence of these factors on specific activity.
  • 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:
    • Wilhelm, W. W.
    • Varvel, G. E.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 1
  • Year: 2011
  • Summary: Emphasis and interest in carbon (C) and nitrogen (N) storage (sequestration) in soils has greatly increased in the last few years, especially C with its' potential to help alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. Several questions still exist with regard to what management practices optimize C storage in the soil profile. A long-term rainfed study conducted in eastern Nebraska provided the opportunity to determine both the effects of different tillage treatments and cropping systems on soil N and soil organic C (SOC) levels throughout the soil profile. The study included six primary tillage systems (chisel, disk, plow, no-till, ridge-till, and subtill) with three cropping systems [continuous corn (CC), continuous soybean (CSB), and soybean-corn (SB-C)]. Soil samples were collected to a depth of 150-cm in depth increments of 0-15-, 15-30-, 15-30-, 30-60-, 60-90-, 90-120-, and 120-150-cm increments and composited by depth in the fall of 1999 after harvest and analyzed for total N and SOC. Significant differences in total N and SOC levels were obtained between tillage treatments and cropping systems in both surface depths of 0-15-, 15-30-cm, but also in the 30-60-cm depth. Total N and SOC accumulations throughout the profile (both calculated by depth and for equivalent masses of soil) were significantly affected by both tillage treatment and cropping system, with those in no-till the greatest among tillage treatments and those in CC the greatest among cropping systems. Soil N and SOC levels were increased at deeper depths in the profile, especially in those tillage systems with the least amount of soil disturbance. Most significant was the fact that soil N and SOC was sequestered deeper in the profile, which would strongly suggest that N and C at these depths would be less likely to be lost if the soil was tilled.
  • Authors:
    • Hoogmoed, W. B.
    • Cai, D.
    • Zhao, Q.
    • Wang, Y.
    • Zhang, X.
    • Zhang, D.
    • Dai, K.
    • Wang, X.
    • Oenema, O.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 1
  • Year: 2011
  • Summary: Rainfed crop production in northern China is constrained by low and variable rainfall. This study explored the effects of tillage/crop residue and nutrient management practices on maize ( Zea mays L.) yield, water use efficiency (WUE), and N agronomic use efficiency (NAE) at Shouyang Dryland Farming Experimental Station in northern China during 2003-2008. The experiment was set-up using a split-plot design with 3 tillage/crop residue methods as main treatments: conventional, reduced (till with crop residue incorporated in fall but no-till in spring), and no-till (with crop residue mulching in fall). Sub-treatments were 3 NP fertilizer rates: 105-46, 179-78 and 210-92 kg N and P ha -1. Maize grain yields were greatly influenced by the growing season rainfall and soil water contents at sowing. Mean grain yields over the 6-year period in response to tillage/crop residue treatments were 5604, 5347 and 5185 kg ha -1, under reduced, no-till and conventional tillage, respectively. Grain yields under no-till, were generally higher (+19%) in dry years but lower (-7%) in wet years. Mean WUE was 13.7, 13.6 and 12.6 kg ha -1 mm -1 under reduced, no-till, and conventional tillage, respectively. The no-till treatment had 8-12% more water in the soil profiles than the conventional and reduced tillage treatments at sowing and harvest time. Grain yields, WUE and NAE were highest with the lowest NP fertilizer application rates (at 105 kg N and 46 kg P ha -1) under reduced tillage, while yields and WUE tended to be higher with additional NP fertilizer rates under conventional tillage, however, there was no significant yield increase above the optimum fertilizer rate. In conclusion, maize grain yields, WUE and NAE were highest under reduced tillage at modest NP fertilizer application rates of 105 kg N and 46 kg P ha -1. No-till increased soil water storage by 8-12% and improved WUE compared to conventional tillage, thus showing potentials for drought mitigation and economic use of fertilizers in drought-prone rainfed conditions in northern China.
  • 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.