• Authors:
    • Liang, Y.
    • Gao, S. R.
    • Bo, C. P.
    • Yang, Y.
    • Wang, S. W.
    • Pan, C. D.
    • Chen, G. A.
  • Source: Xinjiang Agricultural Sciences
  • Volume: 48
  • Issue: 5
  • Year: 2011
  • Summary: Objective: The Purpose of this article is to provide scientific basis for its water and fertilizer management in South of Xinjiang under the condition of oasis irrigation, through analysis of the spatial distribution characteristics of apricot tree absorbing roots in apricot-wheat intercropping systems. Method: With profile digging and layered sampling methods, the spatial distribution of absorbing roots of 15-year-old apricot trees in the intercropping systems is analyzed by using WinRHIZO Pro2009a analysis system. Result: In horizontal directions (0-300 cm), the length density of the absorbing roots in the rows is decreasing with increasing distance from the trees. The maximum root length density is in the 0-50 cm from the trees. The length density of the absorbing roots between the rows is slightly increasing first, and then decreasing with increasing distance from the trees. The maximum root length density is in the 50-100 cm from the trees. The total length of the absorbing roots in the rows is only less 1.11% than it is between the rows. In vertical directions (0-150 cm), the length density of the absorbing roots in the rows and between the rows is increasing first, and then decreasing with increase of soil depth. The maximum root length density in the rows is in the 20-30 cm soil layer, and between the rows is in the 30-40 cm soil layer. Conclusion: Under the condition of oasis irrigation, the spatial distributions of apricot tree absorbing roots are differences between intra-row and inter-row in the intercropping systems, but the differences of total length of the absorbing roots are small. The 0-60 cm soil layer in the 0-120 cm from the trees is important for water and fertilizer management in apricot-wheat intercropping systems. The position of fertilization in the rows and between the rows should be under the crown 2/3-4/5 site at the prosperous fruit stage of apricot trees. The fertilization depth between the rows (30-50 cm) should be deeper about 10-20 cm than in the rows (20-40 cm).
  • Authors:
    • Liscano,J. F.
    • Boquet, D. J.
    • Breitenbeck, G. A.
    • Mascagni, H. J.,Jr.
    • Clawson, E. L.
    • McCarter, K. S.
  • Source: Journal of Plant Nutrition
  • Volume: 34
  • Issue: 6
  • Year: 2011
  • Summary: Soil nitrogen (N)-supplying capacity bioassays could present alternatives to traditional soil tests. Objectives were to identify winter crops and associated characteristics with bioassay potential. Saint Joseph and Bossier City, LA experiments used randomized complete block designs with factorial N fertilizer and winter crop treatment arrangements. Nitrogen rates were applied to corn (Zea mays L.) in 2004. Unfertilized winter wheat (Triticum aestivum L.), cereal rye (Secale cereale L.), native winter vegetation, and weed-free winter fallow treatments followed corn. At Saint Joseph, cotton (Gossypium hirsutum L.) followed winter crop treatments. Greater corn N rate consistently increased winter crop biomass and N accumulation, suggesting potential as bioassays, and increased Saint Joseph seedcotton yield. Winter crop-seedcotton yield N-response relationships were non-significant by familywise error rate criteria. However, some winter crop characteristics, such as rye N accumulation, for which a relationship to seedcotton yield closely approached significance, may merit further research as soil N-supplying capacity bioassays.
  • Authors:
    • Klein, D.
    • Dech, S.
    • Colditz, R. R.
    • Conrad, C.
    • Vlek, P. L. G.
  • Source: International Journal of Remote Sensing
  • Volume: 32
  • Issue: 23
  • Year: 2011
  • Summary: Crop cover and crop rotation mapping is an important and still evolving field in remote sensing science for which robust and highly automated processing chains are required. This study presents an improved mapping procedure for crop rotations of irrigated areas in Central Asia by using classification and regression trees (CARTs) applied to transformations of 250 m Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) time series. The time series were divided into several temporal segments, from which metrics were derived as input features for classification. This temporal aggregation was applied to suppress within-class temporal variability. Various lengths of temporal segments were tested for their potential to increase classification accuracy. In addition, tests of enhancing the classification accuracy were done by combining different classification results using the majority rule for voting. These different processing strategies were applied to four annual time series (2004-2007) of the Khorezm region, where 270 000 ha of irrigated land is dominated by rotations of cotton, wheat and rice. Improved classification results were obtained for CARTs applied to metrics derived from a mixture of different segment lengths. The sole use of either long or short temporal segments was inferior. CART prioritized segments representing active phases of the phenological development. The best result, the optimized segment-based approach, achieved an overall accuracy between 83 and 85% for classifications between 2004 and 2007; in particular, the small range demonstrated the robustness regarding inter-annual variations. These accuracies exceeded those of the original time series without temporal segmentation by 6-7%. With some adjustments to other crops and field heterogeneity influencing the usefulness of a respective sensor, the approach can be applied to other irrigation systems in Central Asia.
  • Authors:
    • Lucas, P.
    • Montfort, F.
    • Jeuffroy, M.-H.
    • Goulevant, G.
    • Reynaud, A.
    • Jacquet, F.
    • De Cara, S.
  • Source: Environmental Modeling & Assessment
  • Volume: 16
  • Issue: 1
  • Year: 2011
  • Summary: This paper addresses the question of summer cover-crop adoption by farmers in presence of a risk of yield loss due to take-all disease and climate variability. To analyze the public incentives needed to encourage farmers to adopt summer cover crops as a means of reducing N leaching, we combine outputs from an economic, an epidemiological and an agronomic model. The economic model is a simple model of choice under risk. The farmer is assumed to choose among a range of summer fallow managements and input uses on the basis of the expected utility criterion (HARA assumption) in presence of both climate and take-all risks. The epidemiological model proposed by Enna
  • Authors:
    • Paustian, K.
    • Ogle, S.
    • Lee, J.
    • De Gryze, S.
    • Six, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 144
  • Issue: 1
  • Year: 2011
  • Summary: We predicted changes in yields and direct net soil greenhouse gas (GHG) fluxes from converting conventional to alternative management practices across one of the world's most productive agricultural regions, the Central Valley of California, using the DAYCENT model. Alternative practices included conservation tillage, winter cover cropping, manure application, a 25% reduction in N fertilizer input and combinations of these. Alternative practices were evaluated for all unique combinations of crop rotation, climate, and soil types for the period 1997-2006. The crops included were alfalfa, corn, cotton, melon, safflower, sunflower, tomato, and wheat. Our predictions indicate that, adopting alternative management practices would decrease yields up to 5%. Changes in modeled SOC and net soil GHG fluxes corresponded to values reported in the literature. Average potential reductions of net soil GHG fluxes with alternative practices ranged from -0.7 to -3.3 Mg CO(2)-eq ha(-1) yr(-1) in the Sacramento Valley and -0.5 to -2.5 Mg CO(2)-eq ha(-1) yr(-1) for the San Joaquin Valley. While adopting a single alternative practice led to modest net soil GHG flux reductions (on average -1 Mg CO(2)-eq ha(-1) yr(-1)), combining two or more of these practices led to greater decreases in net soil GHG fluxes of up to -3 Mg CO(2)-eq ha(-1) yr(-1). At the regional scale, the combination of winter cover cropping with manure application was particularly efficient in reducing GHG emissions. However, GHG mitigation potentials were mostly non-permanent because 60-80% of the decreases in net soil GHG fluxes were attributed to increases in SOC, except for the reduced fertilizer input practice, where reductions were mainly attributed to decreased N(2)O emissions. In conclusion, there are long-term GHG mitigation potentials within agriculture, but spatial and temporal aggregation will be necessary to reduce uncertainties around GHG emission reductions and the delivery risk of the associated C credits. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Barford, C. C.
    • Sacks, W. J.
    • Deryng, D.
    • Ramankutty, N.
  • Source: Global Biogeochemical Cycles
  • Volume: 25
  • Issue: 2
  • Year: 2011
  • Summary: Climate change is expected to significantly impact global food production, and it is important to understand the potential geographic distribution of yield losses and the means to alleviate them. This study presents a new global crop model, PEGASUS 1.0 (Predicting Ecosystem Goods And Services Using Scenarios) that integrates, in addition to climate, the effect of planting dates and cultivar choices, irrigation, and fertilizer application on crop yield for maize, soybean, and spring wheat. PEGASUS combines carbon dynamics for crops with a surface energy and soil water balance model. It also benefits from the recent development of a suite of global data sets and analyses that serve as model inputs or as calibration data. These include data on crop planting and harvesting dates, crop-specific irrigated areas, a global analysis of yield gaps, and harvested area and yield of major crops. Model results for present-day climate and farm management compare reasonably well with global data. Simulated planting and harvesting dates are within the range of crop calendar observations in more than 75% of the total crop-harvested areas. Correlation of simulated and observed crop yields indicates a weighted coefficient of determination, with the weighting based on crop-harvested area, of 0.81 for maize, 0.66 for soybean, and 0.45 for spring wheat. We found that changes in temperature and precipitation as predicted by global climate models for the 2050s lead to a global yield reduction if planting and harvesting dates remain unchanged. However, adapting planting dates and cultivar choices increases yield in temperate regions and avoids 7-18% of global losses.
  • Authors:
    • Maldaner, G. L.
    • Spera, S. T.
    • Fontaneli, R. S.
    • dos Santos, H. P.
  • Source: PESQUISA AGROPECUARIA BRASILEIRA
  • Volume: 46
  • Issue: 10
  • Year: 2011
  • Summary: The objective of this work was to assess energy conversion and balance of integrated crop-livestock production systems, under no-tillage. The experiment was carried out from 2001 to 2008. From 2001 to 2002, the following systems were evaluated: 1, wheat/soybean, and black oat pasture+common vetch/corn; 2, wheat/soybean, and black oat pasture+common vetch+ryegrass/corn; 3, wheat/soybean and black oat pasture+common vetch/millet pasture; 4, wheat/soybean and black oat pasture+common vetch+rygrass/millet pasture; 5, wheat/soybean, white oat/soybean, and black oat pasture+common vetch/millet pasture; 6, wheat/soybean, white oat/soybean, and black oat pasture+common vetch+rygrass/millet pasture. From 2003 to 2008, the following systems were evaluated: 1, wheat/soybean, and common vetch/corn; 2, wheat/soybean, and black oat pasture/corn; 3, wheat/soybean, and black oat pasture/soybean; 4, wheat/soybean, and field pea/corn; 5, wheat/soybean, common vetch/soybean, and double purpose triticale/soybean; and 6, wheat/soybean, double purpose white oat/soybean, and double purpose wheat/soybean. Corn showed highest returned energy in comparison to the other grain crops, and to winter and summer annual pastures. Of the winter cover crops and green manure species evaluated, field pea was the most efficient in energy conversion. Systems 1, 2, and 4, from 2003 to 2008, had the most efficient energy balance.
  • Authors:
    • Linden, B.
    • Aronsson, H.
    • Stenberg, M.
    • Engstrom, L.
  • Source: Agronomy for Sustainable Development
  • Volume: 31
  • Issue: 2
  • Year: 2011
  • Summary: Nitrate leaching after winter oilseed rape and peas has not been studied at the most northern limits of oilseed rape cultivation where winters vary between being mild, with continuous drainage, and cold, with periods of frozen soil. Here, we studied the effect of N fertilisation to oilseed rape, catch crops after oilseed rape and peas and dired drilling of winter wheat after oilseed rape on N leaching in south-west Sweden. Nitrate leaching was determined in two field experiments, dated 2004-2006 and 2005-2007, respectively, on a sandy loam. Our results show that under oilseed rape nitrate leaching was low, at 16-23 kg N ha(-1), in a mild winter with drainage from October to March. In the subsequent mild winter nitrate leaching under wheat was higher, amounting to 35-94 kg N ha(-1). Nitrate leaching levels were similar, 32-58 kg N ha(-1), for all crops in a cold winter with a long-lasting snow cover and main drainage occurring after snowmelt in March and April. Application of fertiliser N to oilseed rape at the optimum N rate, rather than 50 kg N ha(-1) above optimum, reduced leaching in a following winter wheat crop by 25 and 27 kg N ha(-1) in a cold and a mild winter, respectively. Spring undersowing of perennial ryegrass as a catch crop reduced leaching by 12 kg N ha(-1) after optimally fertilised oilseed rape in a mild winter, despite only growing until mid-September when winter wheat was sown. An undersown catch crop of peas, then grown until November, reduced leaching by 15 kg N ha(-1). Direct drilling of winter wheat after oilseed rape had no effect. These findings show that there are risks of enhanced leaching in early spring after a cold winter with a snow cover and superficially frozen soil. Optimising the spring N rate for oilseed rape was the most effective measure to decrease leaching in both mild and cold winters, and this effect was improved by an undersown catch crop in a mild winter.
  • Authors:
    • Leifert, C.
    • Critchley, C. N. R.
    • Eyre, M. D.
    • Wilcockson, S. J.
  • Source: European Journal of Agronomy
  • Volume: 34
  • Issue: 3
  • Year: 2011
  • Summary: A survey of 128 plots, in 2008, of a trial where the effects of crop protection can be separated from those of fertility management, generated weed cover data within six crops (winter wheat, winter barley, spring barley, potatoes, cabbages and a grass/clover ley). The effects of the 2008 crop types, of the two preceding crops and of organic and conventional crop protection and fertility management, were assessed using mixed-effects models and constrained ordination. Cover data for 22 weed species and for monocotyledon, dicotyledon, annual, perennial and total weed cover were used. Cover of 15 weed species, and of the five weed groups, was significantly affected by 2008 crops, with cover highest in spring beans and cabbage. Nine and four weed species 2008 cover were significantly related to crops grown in 2007 and 2006 respectively, as were dicotyledon, annual and total weed cover, but not monocotyledon or perennial cover. Cover of 15 species, and the five groups, was significantly higher in plots with organic crop protection, but only eight species and annuals were significantly affected by fertility management. Crop:crop protection produced the most significant interactions with most cover in organically managed plots. Five species, perennials and total weed cover produced significant three-factor models. The greatest weed cover was in organic crop protected but conventionally fertilised spring barley and the least in totally conventional winter barley. Other factors such as crop density and mechanical weeding also affected 2008 weed cover. The ordination indicated that most of the 22 species were strongly associated with crops from all three years. The sequence of crops in the rotation had a profound effect on weed cover. Where three spring-sown, difficult to weed, crops were grown in sequence (spring beans, potatoes and vegetables, spring barley) weed cover increased. However, cover was limited in grass/clover and some cereal plots with different preceding crops. Models predicting weed cover may need to take into account crop sequences within crop rotations, as well as the more usual management inputs. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Kumar, V.
    • Kumar, V.
    • Saharawat, Y. S.
    • Ladha, J. K.
    • Gathala, M. K.
    • Sharma, P. K.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 5
  • Year: 2011
  • Summary: Rice-wheat (Oryza sativa L.-Triticum aestivum L.) rotation is the major production system in Asia, covering about 18 million ha. Conventional practice of growing rice (puddled transplanting) and wheat (conventional till, CT) deteriorate soil physical properties, and are input- and energy-intensive. Zero-tillage (ZT) along with drill-seeding have been promoted to overcome these problems. A 7-yr permanent plot study evaluated various tillage and crop establishment (CE) methods on soil physical properties with an aim to improve soil health and resource-use efficiency. Treatments included transplanting and direct-seeding of rice on flat and raised beds with or without tillage followed by wheat in CT and ZT soil. Bulk density (D(b)) of the 10- to 20-cm soil layer was highest under puddled treatments (1.74-1.77 Mg m(-3)) and lowest under ZT treatments (1.66-1.71 Mg m(-3)). Likewise, soil penetration resistance (SPR) was highest at the 20-cm depth in puddled treatments (3.46-3.72 MPa) and lowest in ZT treatments (2.51-2.82 MPa). Compared with conventional practice, on average, water-stable aggregates (WSAs) > 0.25 mm were 28% higher in ZT direct-seeding with positive time trend of 4.02% yr(-1). Infiltration was higher (0.29-0.40 cm h(-1)) in ZT treatments than puddled treatments (0.18 cm h(-1)). The least-limiting water range was about double in ZT direct-seeding than that of conventional practice. Gradual improvement in soil physical parameters in ZT system resulted in improvement in wheat yield and is expected to be superior in long-run on system (rice+wheat) basis. Further research is needed to understand mechanisms and requirements of two cereals with contrasting edaphic requirements in their new environment of ZT direct-seeding.