• Authors:
    • Yawson, D. O.
    • Obiri, S.
    • Yengoh, G. T.
    • Odoi, J. O.
    • Armah, F. A.
    • Afrifa, E. K. A.
  • Source: Mitigation and Adaptation Strategies for Global Change
  • Volume: 16
  • Issue: 3
  • Year: 2011
  • Summary: Desertification, climate variability and food security are closely linked through drought, land cover changes, and climate and biological feedbacks. In Ghana, only few studies have documented these linkages. To establish this link the study provides historical and predicted climatic changes for two drought sensitive agro-ecological zones in Ghana and further determines how these changes have influenced crop production within the two zones. This objective was attained via Markov chain and Fuzzy modelling. Results from the Markov chain model point to the fact that the Guinea savanna agro-ecological zone has experienced delayed rains from 1960 to 2008 while the Sudan savanna agro-ecological zone had slightly earlier rains for the same period. Results of Fuzzy Modelling indicate that very suitable and moderately suitable croplands for millet and sorghum production are evenly distributed within the two agro-ecological zones. For Ghana to adapt to climate change and thereby achieve food security, it is important to pursue strategies such as expansion of irrigated agricultural areas, improvement of crop water productivity in rain-fed agriculture, crop improvement and specialisation, and improvement in indigenous technology. It is also important to encourage farmers in the Sudan and Guinea Savanna zones to focus on the production of cereals and legumes (e.g. sorghum, millet and soybeans) as the edaphic and climatic factors favour these crops and will give the farmers a competitive advantage. It may be necessary to consider the development of the study area as the main production and supply source of selected cereals and legumes for the entire country in order to free lands in other regions for the production of crops highly suitable for those regions on the basis of their edaphic and climatic conditions.
  • Authors:
    • Jha, N.
    • Kundu, S. S.
    • Singh, S.
    • Gupta, A.
  • Source: The Indian Journal of Animal Sciences
  • Volume: 81
  • Issue: 11
  • Year: 2011
  • Summary: Seventeen feed ingredients comprising protein sources (linseed cake-LSC, mustard seed cake-MSC, cotton seed cake-CSC, soybean cake-SBC and groundnut cake-GNC), energy sources (deoiled rice bran-DORB, maize grain-MG, barley grain-BG and wheat bran-WB), legume roughages (berseem, cowpea hay-CH, Stylosanthes hamata-SH and Acacia catechu-AC) and non-legume roughages (ammoniated wheat straw-AWS, guinea grass-GG maize fodder-MF and sorghum fodder-SF) were evaluated for carbohydrate and nitrogen fractions as well as mineral contents. In CNCP system, crude protein content of feed is partitioned into 5 fractions (A, B 1, B 2, B 3 and C) and carbohydrate into 4 fractions (A, B 1, B 2 and C) according to degradation rates. The proximate composition, cell wall constituents, carbohydrate and nitrogen fractions of different feeds vary significantly amongst the groups. The CHO, C NSC, C B1, and Cc fractions of carbohydrate were higher in energy, while C A and C B2 fraction of CHO were more in protein sources. Total CHO and C B2 fraction of carbohydrates were more in non-legume while C A, C NSC and Cc fractions were higher in legume roughages. Amongst the studied feedstuffs P A and P B fractions of protein were higher in protein sources, while P B2, P B3 and P C fractions were higher in energy sources. Legumes exhibited higher contents of P B2, while non-legume had higher P A, P B1 and P B3 fraction of protein. Concentration of macro (%) and micro minerals (ppm) of feed stuffs differed across feeds (energy and protein) and roughages (legumes and non legumes). It is concluded from the present study that feedstuffs chemical properties for carbohydrate and nitrogen fractions are unique and different. Therefore feed ingredients selection based on CNCPS evaluation will be more logical for formulating efficient diets for livestock.
  • Authors:
    • Dela Piccolla, C.
    • Mafra, A. L.
    • Pelissari, A.
    • de Moraes, A.
    • da Veiga, M.
    • Balbinot Junior, A. A.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 46
  • Issue: 10
  • Year: 2011
  • Summary: The objective of this work was to evaluate the effect of winter land use on the amount of residual straw, the physical soil properties and grain yields of maize, common bean and soybean summer crops cultivated in succession. The experiment was carried out in the North Plateau of Santa Catarina state, Brazil, from May 2006 to April 2010. Five strategies of land use in winter were evaluated: intercropping with black oat + ryegrass + vetch, without grazing and nitrogen (N) fertilization (intercropping cover); the same intercropping, with grazing and 100 kg ha(-1) of N per year topdressing (pasture with N); the same intercropping, with grazing and without nitrogen fertilization (pasture without N); oilseed radish, without grazing and nitrogen fertilization (oilseed radish); and natural vegetation, without grazing and nitrogen fertilization (fallow). Intercropping cover produces a greater amount of biomass in the system and, consequently, a greater accumulation of total and particulate organic carbon on the surface soil layer. However, land use in winter does not significantly affect soil physical properties related to soil compaction, nor the grain yield of maize, soybean and common bean cultivated in succession.
  • Authors:
    • Joshi, O. P.
    • Billore, S. D.
    • Bhatia, V. S.
    • Ramesh, A.
  • Source: Soybean Research
  • Volume: 9
  • Year: 2011
  • Summary: The work done so far on soybean-based intercropping systems in India involving crops like sorghum, maize, pigeonpea, pearl millet, cotton, sugarcane, minor millets, wheat, rice, oilseeds and plantation crops is reviewed. The compilation brings out the possibilities of rational utilization of natural resources by resorting to diversified cultivation rather than monoculture of crops. Soybean being a short duration leguminous crop with wide agro-climatic adaptability, offers a good opportunity to fit in cropping systems in different regions with added advantage of better economic returns, risk coverage and utilization of natural resources. The benefits of sustainability can be harnessed by adoption of scientifically evaluated and suggested intercropping systems.
  • Authors:
    • Nogueira, C. C. P.
    • Veloso, M. E. da C.
    • Freire Filho, F. R.
    • Cardoso, M. J.
    • Blanco, F. F.
    • Dias, N. da S.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 46
  • Issue: 5
  • Year: 2011
  • Summary: The objective of this work was to evaluate the response of green maize ( Zea mays) intercropped with cowpea ( Vigna unguiculata) to irrigation depths and phosphorus doses. The experiments were carried out in 2008 and 2009 in a randomized block design, with 25 treatments and four replicates. Treatments consisted of five irrigation depths at 70, 110, 140, 180 and 220% of the crop evapotranspiration, and of five doses of P 2O 5: 0, 50, 100, 150 and 200% of the recommended P dose. Maize was sown at 0.80*0.40 m spacing, and cowpea was planted inside the lines among maize plants. There was no effect of P 2O 5 doses, but the response to irrigation depths was quadratic for maize and linear for cowpea. The maximum technical yield of green ears of maize with straw (10.76 Mg ha -1) and without straw (7.62 Mg ha -1) was obtained with 530 mm depth, intermediary to the 180 and 220% of the crop evapotranspiration. The highest cowpea green grain (3.40 Mg ha -1) was obtained with the highest water depth, of 644 mm.
  • Authors:
    • Lal, R.
    • Jagadamma, S.
  • Source: Biology and Fertility of Soils
  • Volume: 46
  • Issue: 6
  • Year: 2010
  • Summary: Soil organic carbon (SOC) is distributed heterogeneously among different-sized primary particles and aggregates. Further, the SOC associated with different physical fractions respond differently to managements. Therefore, this study was conducted with the objective to quantify the SOC associated with all the three structural levels of SOC (particulate organic matter, soil separates and aggregate-size fractions) as influenced by long-term change in management. The study also aims at reevaluating the concept that the SOC sink capacity of individual size-fractions is limited. Long-term tillage and crop rotation effects on distribution of SOC among fractions were compared with soil from adjacent undisturbed area under native vegetation for the mixed, mesic, Typic Fragiudalf of Wooster, OH. Forty five years of no-till (NT) management resulted in more SOC accumulation in soil surface (0-7.5 cm) than in chisel tillage and plow tillage (PT) treatments. However, PT at this site resulted in a redistribution of SOC from surface to deeper soil layers. The soils under continuous corn accumulated significantly more SOC than those under corn-soybean rotation at 7.5-45 cm depth. Although soil texture was dominated by the silt-sized particles, most of the SOC pool was associated with the clay fraction. Compared to PT, the NT treatment resulted in (i) significantly higher proportion of large macroaggregates (>2,000 m) and (ii) 1.5-2.8 times higher SOC concentrations in all aggregate-size classes. A comparative evaluation using radar graphs indicated that among the physical fractions, the SOC associated with sand and silt fractions quickly changed with a land use conversion from native vegetation to agricultural crops. A key finding of this study is the assessment of SOC sink capacity of individual fractions, which revealed that the clay fraction of agricultural soils continues to accumulate more SOC, albeit at a slower rate, with progressive increase in total SOC concentration. However, the clay fraction of soil under native woodlot showed an indication for SOC saturation. The data presented in this study from all the three structural levels of SOC would be helpful for refining the conceptual pool definitions of the current soil organic matter prediction models.
  • Authors:
    • Lal, R.
    • Ussiri, D. A. N.
    • Trumbore, S. E.
    • Mestelan, S.
    • Jagadamma, S.
  • Source: Biogeochemistry
  • Volume: 98
  • Issue: 1-3
  • Year: 2010
  • Summary: Accurate quantification of different soil organic carbon (SOC) fractions is needed to understand their relative importance in the global C cycle. Among the chemical methods of SOC fractionation, oxidative degradation is considered more promising because of its ability to mimic the natural microbial oxidative processes in soil. This study focuses on detailed understanding of changes in structural chemistry and isotopic signatures of SOC upon different oxidative treatments for assessing the ability of these chemicals to selectively isolate a refractory fraction of SOC. Replicated sampling (to ~1 m depth) of pedons classified as Typic Fragiudalf was conducted under four land uses (woodlot, grassland, no-till and conventional-till continuous corn [ Zea mays L.]) at Wooster, OH. Soil samples (<2 mm) were treated with three oxidizing agents (hydrogen peroxide (H 2O 2), disodium peroxodisulfate (Na 2S 2O 8) and sodium hypochlorite (NaOCl)). Oxidation resistant residues and the bulk soil from A1/Ap1 horizons of each land use were further analyzed by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and accelerator mass spectrometry to determine structural chemistry and 14C activity, respectively. Results indicated that, oxidation with NaOCl removed significantly less SOC compared to Na 2S 2O 8 and H 2O 2. The NMR spectra revealed that NaOCl oxidation preferentially removed lignin-derived compounds at 56 ppm and at 110-160 ppm. On the other hand, the SOC resistant to Na 2S 2O 8 and H 2O 2 oxidation were enriched with alkyl C groups, which dominate in recalcitrant macromolecules. This finding was corroborated by the 14C activity of residual material, which ranged from -542 to -259 per mil for Na 2S 2O 8 resistant SOC and -475 to -182 per mil for H 2O 2 resistant SOC as compared to relatively greater 14C activity of NaOCl resistant residues (-47 to 61 per mil). Additionally, H 2O 2 treatment on soils after light fraction removal was more effective in isolating the oldest ( 14C activity of -725 to -469 per mil) SOC fraction. The Delta 14C signature of SOC removed by different oxidizing agents, calculated by mass balance, was more or less similar irrespective of the difference in labile SOC removal efficiency. This suggests that SOC isolated by many fractionation methods is still a mixture of much younger and older material and therefore it is very important that the labile SOC should be completely removed before measuring the turnover time of stable and refractory pools of SOC.
  • Authors:
    • Kadasrivenkata, H.
    • Kapanigowda, M.
    • Stewart, B. A.
    • Howell, T. A.
    • Baumhardt, R. L.
  • Source: Field Crops Research
  • Volume: 118
  • Issue: 2
  • Year: 2010
  • Summary: Under dryland conditions of the Texas High Plains, maize ( Zea mays) production is limited by sparse and erratic precipitation that results in severe water stress particularly during grain formation. When plant populations are reduced to 2.0-3.0 plants m -2 to conserve soil water for use during grain filling, tillers often form during the vegetative growth and negate the expected economic benefit. We hypothesized that growing maize in clumps spaced 1.0 m apart would reduce tiller formation, increase mutual shading among the plants, and conserve soil water for grain filling that would result in higher grain yield. Studies were conducted during 2006 and 2007 at Bushland, TX. with two planting geometries (clump vs. equidistant), two irrigation methods (low-energy precision applicator, LEPA, and low-elevation spray applicator, LESA) at three irrigation levels (dryland, 75 mm and 125 mm in 2006; and dryland, 50 mm and 100 mm in 2007). For dryland plots in 2007, clump plants had only 0.17 tillers (0.66 tillers m -2) compared with 1.56 tillers per plant (6.08 tillers m -2) for equidistant spacing. Tillers accounted for 10% of the stover for the equidistant plants, but less than 3% of the grain. Clump planting produced significantly greater grain yields (321 g m -2 vs. 225 g m -2 and 454 g m -2 vs. 292 g m -2 during 2006 and 2007, respectively) and Harvest Indexes (0.54 vs. 0.49 and 0.52 vs. 0.39 during 2006 and 2007, respectively) compared with equidistant plants in dryland conditions. Water use efficiency (WUE) measurements in 2007 indicated that clumps had a lower evapotranspiration (ET) threshold for initiating grain production, but the production function slopes were 2.5 kg m -3 for equidistant treatments compared to 2.0 kg m -3 for clump treatments. There was no yield difference for method of irrigation on water use efficiency. Our results suggest that growing maize in clumps compared with equidistant spacing reduced the number of tillers, early vegetative growth, and Leaf Area Index (LAI) so that more soil water was available during the grain filling stage. This may be a useful strategy for growing maize with low plant populations in dryland areas where severe water stress is common.
  • Authors:
    • Keleman, A.
  • Source: Agriculture and Human Values
  • Volume: 27
  • Issue: 1
  • Year: 2010
  • Summary: One of the major adjustments brought on by the North American Free Trade Agreement (NAFTA) was a change in the relationship between Mexican agricultural support institutions and the small-scale agricultural sector. Post-NAFTA restructuring programs sought to correct previous inefficiencies in this sector, but they have also had the effect of marginalizing the producers who steward and manage the country's reserve of maize ( Zea mays) genetic diversity. Framed by research suggesting that certain maize varieties in a rain-fed farming region in southern Sonora are in danger of loss due chiefly to long-term drought, this article explores the ramifications of post-NAFTA agricultural policies for in situ maize diversity conservation. Qualitative methods, including semi-structured interviews with agricultural support institutions and participant observation with farmers, were used to gather data on dryland farmers' access to research and extension, as well as possibilities for collective action. In southern Sonora, agricultural support is oriented primarily toward high-tech production, and there are structural barriers to small-scale farmers' access to research and extension institutions. Further, collective action around agriculture is limited. These circumstances represent significant limitations to farmers' options for accessing new techniques which might help maintain maize diversity in the context of economic and environmental change.
  • Authors:
    • Wang, L.
    • van Ranst, E.
    • Li, C.
    • Tang, H.
    • Li, H.
    • Qiu, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 135
  • Issue: 1-2
  • Year: 2010
  • Summary: Agricultural production plays an important role in affecting atmospheric greenhouse gas concentrations. Field measurements were conducted in Quzhou County, Hebei Province in the North China Plains to quantify carbon dioxide (CO 2) and nitrous oxide (N 2O) emissions from a winter wheat-maize rotation field, a common cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, Denitrification-Decomposition or DNDC, for its applicability for the cropping system. The validated DNDC was then used for predicting impacts of three management alternatives (i.e., no-till, increased crop residue incorporation and reduced fertilizer application rate) on CO 2 and N 2O emissions from the target field. Results from the simulations indicated that (1) CO 2 emissions were significantly affected by temperature, initial SOC, tillage method, and quantity and quality of the organic matter added in the soils; (2) increases in temperature, initial SOC, total fertilizer N input, and manure amendment substantially increased N 2O emissions; and (3) temperature, initial SOC, tillage, and quantity and quality of the organic matter added in the soil all had significant effects on global warming. Finally, five 50-year scenarios were simulated with DNDC to predict their long-term impacts on crop yield, soil C dynamics, nitrate leaching losses, and N 2O emissions. The modelled results suggested that implementation of manure amendment or crop residue incorporation instead of increased fertilizer application rates would more efficiently mitigate GHG emissions from the tested agro-ecosystem. The multi-impacts provided a sound basis for comprehensive assessments on the management alternatives.