• Authors:
    • Armentano, G.
  • Source: L'Informatore Agrario
  • Volume: 68
  • Issue: 1
  • Year: 2012
  • Authors:
    • Begue, A.
    • Dubreuil, V.
    • Meirelles, M.
    • Arvor, D.
    • Shimabukuro, Y. E.
  • Source: Applied Geography
  • Volume: 32
  • Issue: 2
  • Year: 2012
  • Summary: The Amazonian state of Mato Grosso is the main production area for soybeans in Brazil and contains 31.3% of the national production as of 2009. The rapid evolution of the agricultural systems in this area shows that the region is experiencing a rapid agricultural transition. In this paper, we broke down this transition process into three steps: crop expansion, agricultural intensification and ecological intensification. We used remote sensing products to develop and compute satellite-derived indices describing the main agricultural dynamics during the cropping years from 2000-2001 to 2006-2007. Our results indicated that Mato Grosso is continuing to expand its agricultural sector, with a 43% increase in the net cropped area during the study period. Although this expansion mainly occurred in the cerrado ecoregion until the early 2000s, the forest ecoregion is experiencing expansion at this time. We observed that 65% of the crop expansion in Mato Grosso from 2000 to 2006 occurred in this ecoregion. However, we did not identify this crop expansion as the major driver of deforestation in Mato Grosso because only 12.6% of the cleared areas were directly converted into croplands. Agricultural intensification also evolved rapidly, as the proportion of the net cropped area cultivated with double cropping systems harvesting two successive commercial crops (i.e., soybean and corn or soybean and cotton) increased from 6% to 30% during the study period. Finally, we found that ecological intensification occurred because the region's farmers planted a non-commercial crop (i.e., millet or sorghum) after the soybean harvest to prevent soil erosion, improve soil quality, break pest cycles, maintain soil moisture and set the conditions for high-quality no-tillage operations. In 2006-2007, 62% of the net cropped area was permanently covered by crops during the entire rainy season. This practice allowed the farmers to diversify their production, as shown by the positive evolution of the Area Diversity Index. Future scholars can use the method proposed in this paper to improve their understanding of the forces driving the agricultural dynamics in Mato Grosso.
  • Authors:
    • Tchoundjeu, Z.
    • Kalinganire, A.
    • Coe, R.
    • Sileshi, G. W.
    • Bayala, J.
    • Sinclair, F.
    • Garrity, D.
  • Source: Journal of Arid Environments
  • Volume: 78
  • Year: 2012
  • Summary: To address the decline in crop productivity in the drylands of West Africa, many initiatives have focused on combating soil degradation. Various practices including (1) parkland trees associated with crops, (2) coppicing trees, (3) green manure, (4) mulching. (5) crop rotation and intercropping, and (6) traditional soil/water conservation have been tested. The present study attempts to provide a comprehensive, quantitative synthesis of existing reports on the effect of conservation agriculture (CA) practices on crop yield response in Burkina Faso, Mali, Niger and Senegal. Out of a total of 155 reports found, 63 fulfilled all the appropriate criteria to be included in the meta-analysis of the effect of various conservation agriculture practices on the yield response of maize, millet and sorghum. The study revealed significant variability in cereal yield response (and hence risk) with all the practices examined. Despite the variability, the mean effects of the six CA practices on crop yield were more positive than negative except with parkland trees. However, for this last practice, species like Faidherbia albida exerts more positive impact on crop yield. Yield increases relative to the control were higher with green manure and mulching than with coppicing trees and parklands. Increases in yield in the six CA practices were higher on low to medium productivity sites for maize, millet and sorghum. Coppicing trees and rotations improved yields when the rainfall is >800 mm whereas the opposite happens with parkland and soil-water conservation measures. Mulching performed better when the rainfall is
  • Authors:
    • Rosen, C. J.
    • Bierman, P. M.
    • Venterea, R. T.
    • Lamb, J. A.
  • Source: Agricultural Systems
  • Volume: 109
  • Year: 2012
  • Summary: A survey was conducted in the spring of 2010 to characterize the use of nitrogen (N) fertilizer on corn ( Zea mays L.) by Minnesota farmers in the 2009 growing season. Detailed information on synthetic N fertilizer management practices was collected from interviews with 1496 farmers distributed across all of the corn growing regions in the state. The total amount of corn they grew represented 6.8% of the ha of corn harvested in Minnesota in 2009. This report summarizes data on: (1) N fertilizer rates, (2) major N sources (excluding manures), (3) application timing of the major N source, (4) use of nitrification inhibitors, additives, and specialty N fertilizer formulations, (5) fertilizer placement and incorporation practices, (6) use of starter fertilizer, split and sidedress applications, and other N sources such as ammonium phosphates, (7) N fertilization of irrigated corn, and (8) use of soil testing as a fertility management tool. Many of the survey results are reported as statewide averages, but where regional differences occurred the data are broken down and presented separately for different parts of the state. This survey provides the most comprehensive set of data on N fertilizer use on corn that has been collected in Minnesota. The information can be used to target research and education programs to improve N management for both production and environmental goals. The statewide average N fertilizer rate was 157 kg N ha -1. Variable rate application was used to apply N by 23% of farmers. About 59% of surveyed farmers applied the majority of their N fertilizer in the spring before planting, 32.5% made their main N application in the fall, and 9% sidedressed the majority of their N after corn emergence. Most farmers used anhydrous ammonia (46%) or urea (45%) as their major source of N fertilizer, while 6.5% used a liquid N formulation as their primary N source. Soil testing was used as a fertility management tool on 84% of the surveyed fields in the last 5 years. Overall results indicate that N fertilizer use by Minnesota corn farmers is generally consistent with University of Minnesota Extension N management guidelines. Fertilizer N use could probably be improved by taking adequate N credit for previous soybean crops. In the South Central region of the state, fertilizer N recovery could potentially be improved by increased use of nitrification inhibitors with fall-applied anhydrous ammonia or by delaying anhydrous ammonia application until spring.
  • Authors:
    • Hensley, M.
    • Bennie, A. T. P.
    • Botha, J. J.
    • Rensburg, L. D. van
  • Source: Water SA
  • Volume: 37
  • Issue: 5
  • Year: 2011
  • Summary: This review provides an overview of Water Research Commission (WRC)-funded research over the past 36 years. A total of 28 WRC reports have been consulted, 13 of these compiled by the University of the Free State, 4 by the University of Fort Hare, and the remainder mainly by the ARC-Institute for Soil Climate and Water. This work has resulted in extensive capacity building in this field - numerous technical assistants and 58 researchers have been involved, of which 23 are still active in research. The focus on the water flow processes in the soil-plant-atmosphere continuum (SPAC), with particular emphasis on processes in the soil, has greatly enhanced understanding of the system, thereby enabling the formulation of a quantitative model relating the water supply from a layered soil profile to water demand; the formulation of logical quantitative definitions for crop-ecotope specific upper and lower limits of available water; the identification of the harmful rootzone development effects of compacted layers in fine sandy soils caused by cultivation, and amelioration procedures to prevent these effects; and management strategies to combat excessive water losses by deep drainage. The explanation of the way in which SPAC is expressed in the landscape in the form of the ecotope has been beneficial with regard to the extrapolation of studies on particular SPACs to the large number of ecotopes where detailed studies have not been possible. Valuable results are reported regarding rainfall and runoff management strategies. Longer fallow periods and deficit irrigation on certain crop ecotopes improved rainfall use efficiency. On semi-arid ecotopes with high-drought-risk clay and duplex soils and high runoff losses, in-field rainwater harvesting (IRWH), designed specifically for subsistence farmers, resulted in maize and sunflower yield increases of between 30% and 50% compared to yields obtained with conventional tillage. An indication of the level of understanding of the relevant processes that has been achieved is demonstrated by their quantitative description in mathematical and empirical models: BEWAB for irrigation, SWAMP mainly for dryland cropping, and CYP-SA for IRWH. Five important related research and development needs are identified. The WRC has played, and continues to play, an important role in commissioning and funding research on water utilisation in agriculture and has clearly made an excellent contribution to the progress made in addressing the needs and requirements of subsistence, emergent and dryland farmers in South Africa.
  • Authors:
    • Mehrabi,P.
    • Daliri,M. S.
    • Homayoun,H.
  • Source: Middle-East Journal of Scientific Research
  • Volume: 9
  • Issue: 3
  • Year: 2011
  • Summary: To measure the relationship between chlorophyll stress resistances in experimental maize cultivars Using 5 Maize genotypes in four replications and with two irrigation and dry farming conditions in a randomized complete block design in the 2010-2011 agricultural years in Ardabil region was carried out. To calculate the amount of stress tolerance of genotypes has been used of Fernandez stress tolerance indexes. And the chlorophyll content of leaves with the CCI-200 device was measured. The results showed that stress-resistant genotypes with higher potential yield and chlorophyll content were more than half resistant cultivars. According to the results of genotypes BC678 and BC404 have a highest chlorophyll index and the amount of yield and the most resistant genotypes to the drought.
  • Authors:
    • Hu, H.
    • Tian, S.
    • Zhong, W.
    • Li, Z.
    • Ning, T.
    • Wang, Y.
    • Zhang, Z.
  • Source: Scientia Agricultura Sinica
  • Volume: 44
  • Issue: 9
  • Year: 2011
  • Summary: Objective: The objective of this study was to understand the effects of normal urea and controlled release urea on grain filling rate, yield and water use efficiency of different maize cultivars under different tillage modes. Method: Three sets of treatments were arranged in a split-split plot design. The whole-plot treatment factor was the tillage mode, stubble ploughing or subsoiling after stubble ploughing. The subplot treatment factor was maize cultivars Zhengdan 958 and Denghai 3. The sub-subplot treatment factor was the nitrogen level, including applied with 225 kg N.hm -2 normal urea, applied with 225 kg N.hm -2 controlled release urea, and no nitrogen fertilizer used as control. Result: At the same tillage mode, nitrogen level and maize cultivars, the soil water content in 0-100 cm soil layer applied with controlled release urea was higher at pre-tasselling stage, while lower at maturity stage than those applied with normal urea. It indicated that treatment applied with controlled release urea could realize higher use of soil water through time and space, and as a result increased the gain filling rate and water use efficiency. Subsoiling after stubble ploughing could also increase the grain filling rate and water use efficiency. Compared with Zhengdan 958, Denghai 3 had higher grain filling rate, yield and water use efficiency. And these were positive coupling effects between urea type, subsoiling, and maize cultivars, which was benefit for higher yield in dryland farm. Conclusion: Higher use of soil water through time and space and higher grain filling rate were the important reasons for higher yield and water use efficiency. Using suitable maize cultivars and applying controlled release urea, with subsoiling after stubble ploughing, could make the good use of soil water, and realize the space-time coincide between soil water supply and crop needs, which will be the important measures to achieve higher grain yield and higher benefit in semi-humid region of China.
  • Authors:
    • Kihara, J.
    • Bationo, A.
    • Mugendi, D. N.
    • Martius, C.
    • Vlek, P. L. G.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 90
  • Issue: 2
  • Year: 2011
  • Summary: Smallholder land productivity in drylands can be increased by optimizing locally available resources, through nutrient enhancement and water conservation. In this study, we investigated the effect of tillage system, organic resource and chemical nitrogen fertilizer application on maize productivity in a sandy soil in eastern Kenya over four seasons. The objectives were to (1) determine effects of different tillage-organic resource combinations on soil structure and crop yield, (2) determine optimum organic-inorganic nutrient combinations for arid and semi-arid environments in Kenya and, (3) assess partial nutrient budgets of different soil, water and nutrient management practices using nutrient inflows and outflows. This experiment, initiated in the short rainy season of 2005, was a split plot design with 7 treatments involving combinations of tillage (tied-ridges, conventional tillage and no-till) and organic resource (1 t ha -1 manure + 1 t ha -1 crop residue and; 2 t ha -1 of manure (no crop residue) in the main plots). Chemical nitrogen fertilizer at 0 and 60 kg N ha -1 was used in sub-plots. Although average yield in no-till was by 30-65% lower than in conventional and tied-ridges during the initial two seasons, it achieved 7-40% higher yields than these tillage systems by season four. Combined application of 1 t ha -1 of crop residue and 1 t ha -1 of manure increased maize yield over sole application of manure at 2 t ha -1 by between 17 and 51% depending on the tillage system, for treatments without inorganic N fertilizer. Cumulative nutrients in harvested maize in the four seasons ranged from 77 to 196 kg N ha -1, 12 to 27 kg P ha -1 and 102 to 191 kg K ha -1, representing 23 and 62% of applied N in treatments with and without mineral fertilizer N respectively, 10% of applied P and 35% of applied K. Chemical nitrogen fertilizer application increased maize yields by 17-94%; the increases were significant in the first 3 seasons ( P2 mm) and micro-aggregates fractions (53 m: P tied-ridges > conventional tillage. Also, combining crop residue and manure increased large macro-aggregates by 1.4-4.0 g 100 g -1 soil above manure only treatments. We conclude that even with modest organic resource application, and depending on the number of seasons of use, conservation tillage systems such as tied-ridges and no-till can be effective in improving crop yield, nutrient uptake and soil structure and that farmers are better off applying 1 t ha -1 each of crop residue and manure rather than sole manure.
  • Authors:
    • Kocyigit, R.
    • Rice ,C. W.
  • Source: Bulgarian Journal of Agricultural Science
  • Volume: 17
  • Issue: 4
  • Year: 2011
  • Summary: The soil surface CO 2 flux is the second largest flux in the terrestrial carbon budget after photosynthesis. Plant root and microbial respiration produce CO 2 in soils, which are important components of the global C cycle. This study determined the amount of CO 2 released during spring wheat ( Triticum aestivum L.) growth under no-till (NT) and conventional tillage (CT) systems. This experiment was conducted at Kansas State University North Agronomy Farm, Manhattan, KS, on a Kennebec silt loam. This study site was previously under dry land continuous corn production with NT and CT for more than 10 years. Spring wheat ( Triticum aestivum L.) was planted with two tillage systems (NT and CT) as four replicates in March. Surface CO 2 flux was measured weekly during plant growth. Soil water content at the surface (5 cm) tended to be greater in NT and decreased from planting to harvest. Soil microbial activity at the surface was usually higher in NT and decreased from planting to harvest, while activity was constant in the deeper depths. The higher microbial activity at the surface of NT occurred after 60 days of planting where soil water content was the most limiting factor on microbial activity. Soil CO 2 flux varied in response to changes in soil water content and the variation and magnitude of the increase was greater at higher soil water contents. Conventional tillage released 20% more CO 2 to the atmosphere compare to NT after 10 years in the North American Great Plains Regions.
  • Authors:
    • Lal, R.
  • Source: Food Policy
  • Volume: 36
  • Issue: S1
  • Year: 2011
  • Summary: Soils of the world's agroecosystems (croplands, grazing lands, rangelands) are depleted of their soil organic carbon (SOC) pool by 25-75% depending on climate, soil type, and historic management. The magnitude of loss may be 10 to 50 tons C/ha. Soils with severe depletion of their SOC pool have low agronomic yield and low use efficiency of added input. Conversion to a restorative land use and adoption of recommended management practices, can enhance the SOC pool, improve soil quality, increase agronomic productivity, advance global food security, enhance soil resilience to adapt to extreme climatic events, and mitigate climate change by off-setting fossil fuel emissions. The technical potential of carbon (C) sequestration in soils of the agroecosystems is 1.2-3.1 billion tons C/yr. Improvement in soil quality, by increase in the SOC pool of 1 ton C/ha/yr in the root zone, can increase annual food production in developing countries by 24-32 million tons of food grains and 6-10 million tons of roots and tubers. The strategy is to create positive soil C and nutrient budgets through adoption of no-till farming with mulch, use of cover crops, integrated nutrient management including biofertilizers, water conservation, and harvesting, and improving soil structure and tilth.