• Authors:
    • Amarasekera, P.
    • Sangakkara, U. R.
    • Stamp, P.
  • Source: Acta Agronomica Hungarica
  • Volume: 59
  • Issue: 2
  • Year: 2011
  • Summary: Maize is the most important upland cereal in tropical Asia, grown in both major and minor seasons under rainfed conditions. Due to the inadequate rainfall in the minor season, the crop is subjected to water stress, and irrigation helps to produce high yields. Smallholders who grow maize on flat beds in their allotments often use surface flood irrigation whenever irrigation water is available, which leads in most instances to inefficient use of this valuable resource. A field study was carried out over two minor seasons in Sri Lanka to determine the impact of different schedules of irrigation, developed on the basis of time intervals (3-, 7-, 14- or 21-day intervals or no irrigation as a control), which can easily be practised by smallholders, on the root development, shoot growth, seed yield and water use efficiency of maize. Irrigation at 3-day intervals produced fine roots in the top layers of the soil. Increasing the time interval between irrigation schedules to 7, 14 or 21 days reduced the percentage of fine roots, but developed more, heavier roots in the lower soil layers, as determined by root length densities (RLD) and root weight densities (RWD). Longer irrigation intervals or lack of irrigation resulted in a smaller number of heavier roots in the soil profile. The leaf water potential was affected to a greater degree than shoot water content or relative water content. The seed yield and harvest index were highest when maize was irrigated at 7-day intervals. In contrast, irrigation water use efficiency (IWUE) was highest at an irrigation interval of 14 days. The potential for optimizing water use in surface irrigation in flat beds while obtaining high yields in a tropical Asian minor season, when maize is subjected to moisture stress under smallholding conditions, is presented on the basis of this study.
  • Authors:
    • Cella, A. J. S.
    • Ferraz, E. de C.
    • Barros, H. B.
    • Santos, E. R. dos
    • Capone, A.
    • Santos, A. F. dos
    • Fidelis, R. R.
  • Source: Revista Ceres
  • Volume: 58
  • Issue: 6
  • Year: 2011
  • Summary: The genetic diversity is one of the most important parameters evaluated by plant breeders in the early stages of a genetic improvement program. The objective of this paper was to evaluate the genetic divergence by means of multivariate techniques, among 48 soybean genotypes grown in irrigated lowland in the State of Tocantins, in order to select parents of hybrids for the production of oil and meal, as well as varieties of the panel, intended for human consumption. The experiment was conducted in the county Formoso do Araguaia - Tocantins, Brazil, in the cultivation of irrigated lowland, in the inter-cropping 2010. The experimental design was a randomized block with four replications. There was observed variability among the genotype tested. The Tocher's method, UPGMA and Canonic Variables agreed among themselves, and found four distinct groups. The following hybrids are promising for the production of soybean oil and meal for the M-Soy 8766, M-Soy 9144, A-7002 and M-soy 9056 with Amaralina RR crosses between and M-Soy 8766, M-Soy 9144 and Amaralina RR with BRSMG 790A, BRS 257, BRS 216 and BRS 213, are listed in order especially soybeans for human consumption.
  • Authors:
    • Rosa, I.
    • Carreiras, J. M. B.
    • Silva, J. M. N.
    • Pereira, J. M. C.
  • Source: Journal of Geophysical Research: Atmospheres
  • Volume: 116
  • Issue: D20
  • Year: 2011
  • Summary: Annual emissions of CO(2), CH(4), CO, N(2)O, and NO(x) from biomass burning in shifting cultivation systems in tropical Asia, Africa, and America were estimated at national and continental levels as the product of area burned, aboveground biomass, combustion completeness, and emission factor. The total area of shifting cultivation in each country was derived from the Global Land Cover 2000 map, while the area cleared and burned annually was obtained by multiplying the total area by the rotation cycle of shifting cultivation, calculated using cropping and fallow lengths reported in the literature. Aboveground biomass accumulation was estimated as a function of the duration and mean temperature of the growing season, soil texture type, and length of the fallow period. The uncertainty associated with each model variable was estimated, and an uncertainty and sensitivity analysis of greenhouse gas estimates was performed with Monte Carlo and variance decomposition techniques. Our results reveal large uncertainty in emission estimates for all five gases. In the case of CO(2), mean (standard deviation) emissions from shifting cultivation in Asia, Africa, and America were estimated at 241 (132), 205 (139), and 295 (197) Tg yr(-1), respectively. Combustion completeness and emission factors were the model inputs that contributed the most to the uncertainty of estimates. Our mean estimates are lower than the literature values for atmospheric emission from biomass burning in shifting cultivation systems. Only mean values could be compared since other studies do not provide any measure of uncertainty.
  • Authors:
    • Aster, D.
    • Awulachew, S. B.
    • Erkossa, T.
  • Source: Agricultural Sciences
  • Volume: 2
  • Issue: 3
  • Year: 2011
  • Summary: Maize (Zea mays) is among the major cereals grown in the high rainfall areas of the sub-Saharan Africa's (SSA) such as the Ethiopian part of the Blue Nile basin. However, its productivity is severely constrained by poor soil, water and crop management practices. This study simulated the water productivity of the crop under varying soil fertility scenarios (poor, near optimal and none limiting) using hybrid seeds under rainfed conditions using the FAO Aqua-Crop model. The result indicated that grain yield of maize increased from 2.5 tons.ha -1 under poor to 6.4 and 9.2 tons.ha -1 with near optimal and non-limiting soil fertility conditions. Correspondingly, soil evaporation decreased from 446 mm to 285 and 204 mm, while transpiration increased from 146 to 268 and 355 mm. Consequently, grain water productivity was increased by 48% and 54%, respectively, with the near optimal and non-limiting soil fertility conditions. The water productivity gain mainly comes from reduced evaporation and increased transpiration without significantly affecting water left for downstream ecosystem services. Therefore, this has a huge implication for a basin scale water management planning for various purposes.
  • Authors:
    • Elazegui, D. D.
    • Chupungco, A. R.
    • Nguyen, M. R.
  • Source: Philippine Journal of Crop Science
  • Volume: 36
  • Issue: 2
  • Year: 2011
  • Summary: This study discusses the seed system, production and marketing of eggplant, Solanum melongena L., considered as one of the most important vegetable crops in the Philippines. Data analyzed were obtained from focus group discussions in major eggplant producing provinces of Pangasinan, Batangas and Quezon; key informant interviews with representatives of government agencies and seed companies, and traders; and secondary sources such as government reports and other publications. The eggplant seed system is generally organized, involving public and private sectors. There are different varieties available in the market but seed developers do not opt for seed registration nor plant variety protection because of the rigorous process involved. Instead, seed companies adopt well-established seed production and quality control strategies and vigorous marketing and promotion to improve sales. Commercial growers of eggplant adopt hybrid seeds, while open-pollinated varieties (OPVs) are mainly used for small-scale production. Between 2000 and 2009, eggplant production increased by 21% despite a relatively lower increase (6%) in area planted. Average yield ranged 8-10 mt ha -1. Eggplant production is profitable, but major problems include fruit and shoot borer (FSB) infestation, bacterial wilt, irrigation supply and climate-related problems. Production involves intensive use of pesticides, bearing some implications on human health and environment. This should call the attention of Local Government Units which are in the forefront of providing extension services. Moreover, research and development should continuously receive adequate support to address these concerns. Research and development thrusts could include varietal improvement of eggplant and alternative pest control strategies such as integrated pest management (IPM) technology and intercropping. The current effort on R & D of Bt eggplant addresses the problem of FSB and heavy dependence of farmers on pesticides. With the stringent regulatory system of the Philippines on the commercial propagation of GM crops, adverse impact on human health and environment will be curtailed.
  • Authors:
    • Rao, I. M.
    • Schmidt, A.
    • van der Hoek, R.
    • Bernasconi, S. M.
    • Frossard, E.
    • Douxchamps, S.
    • Oberson, A.
  • Source: Plant and Soil
  • Volume: 341
  • Issue: 1-2
  • Year: 2011
  • Summary: The integration of multipurpose legumes into low-input tropical agricultural systems is needed because they are a nitrogen (N) input through symbiotic fixation. The drought-tolerant cover legume canavalia (Canavalia brasiliensis) has been introduced for use either as forage or as a green manure into the crop-livestock system of the Nicaraguan hillsides. To evaluate its impact on the subsequent maize crop, an in-depth study on N dynamics in the soil-plant system was conducted. Microplots were installed in a 6-year old field experiment with maize-canavalia rotation. Direct and indirect (15)N-labelling techniques were used to determine N uptake by maize from canavalia residues and canavalia-fed cows' manure compared to mineral fertilizer. Litter bags were used to determine the N release from canavalia residues. The incorporation of N from the amendment into different soil N pools (total N, mineral N, microbial biomass) was followed during the maize cropping season. Maize took up an average of 13.3 g N m(-2), within which 1.0 g N m(-2) was from canavalia residues and 2.6 g N m(-2) was from mineral fertilizer, corresponding to an amendment N recovery of 12% and 32%, respectively. Recoveries in maize would probably be higher at a site with lower soil available N content. Most of the amendment N remained in the soil. Mineral N and microbial N were composed mainly of N derived from the soil. Combined total (15)N recovery in maize and soil at harvest was highest for the canavalia residue treatment with 98% recovery, followed by the mineral fertilizer treatment with 83% recovery. Despite similar initial enrichment of soil microbial and mineral N pools, the indirect labelling technique failed to assess the N fertilizer value of mineral and organic amendments due to a high N mineralization from the soil organic matter.
  • Authors:
    • Wokocha, C. C.
    • Eludoyin, O. S.
  • Source: Asian Journal of Agricultural Sciences
  • Volume: 3
  • Issue: 2
  • Year: 2011
  • Summary: The present study evaluated the impacts of maize cultivation on soil properties under the continuous monocropping system of farming in South-western Nigeria. Soil samples were collected from both cultivated maize plot and less disturbed secondary forest, both lying contiguous to each other. Laboratory analysis was carried out to determine the levels of particle size composition, porosity, bulk density; and concentrations of Cations Exchange Capacity (CEC), Exchangeable Sodium (Na), Exchangeable Calcium (Ca), Exchangeable Magnesium (Mg), Available Phosphorous (P), Soil pH, Exchangeable Acidity, Organic Carbon (C) and Nitrogen (N). The mean of each of these soil properties was used for comparison and t-test was also used to determine the significant difference that exists in each soil property. The result shows that the level of C, N and porosity were higher in soils under forest than soils under maize. However, there was no significant difference in Exchangeable Acidity, Mg, Soil pH and Ca in the two land use types. Nevertheless, the concentrations of Na and K were higher in the cultivated soils while P and Ca were lower in the cultivated soils. The particle size composition was predominantly sandy. Planting of cover crops, mixed cropping and mulching among others were suggested as ways to minimize erosion and leaching so that fertility can be restored and maintained.
  • Authors:
    • Muthukrishnan, P.
    • Fanish, S. A.
  • Source: Madras Agricultural Journal
  • Volume: 98
  • Issue: 10/12
  • Year: 2011
  • Summary: Field experiments were conducted at Agricultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, during kharif 2008 and 2009 to study the effect of different fertigation levels and intercrops in intensive maize based intercropping system. The experiment was laid out in strip plot design with three replications. The experiment comprised of nine fertigation levels in main plot, viz M 1, Surface irrigation with soil application of 100% RDF; M 2, Drip irrigation with soil application of 100% RDF; M 3, Drip fertigation of 75% RDF; M 4, Drip fertigation of 100% RDF; M 5, Drip fertigation of 125% RDF; M 6, Drip fertigation of 150% RDF; M 7, Drip fertigation of 50% RDF (50% P and K as Water Soluble Fertilizer (WSF)); M8, Drip fertigation of 75% RDF (50% P and K as WSF); M 9, Drip fertigation of 100% RDF (50% P and K as WSF) and four intercrops in sub plot viz, S 1, Vegetable coriander; S 2, Radish; S 3, Beet root; S 4, Onion. Drip fertigation at 100 per cent RDF with 50 per cent P and K as WSF in maize+radish intercropping system recorded a higher gross income of Rs. 83438/ha whereas, higher net return and benefit cost ratio of Rs. 56858 and 3.24, respectively, were recorded by drip fertigation at 150 per cent RDF with radish as intercrop system.
  • Authors:
    • Manoharan, S.
    • Muthukrishnan, P.
    • Fanish, S. A.
  • Source: Indian Journal of Agricultural Research
  • Volume: 45
  • Issue: 3
  • Year: 2011
  • Summary: Field experiments were conducted during kharif 2008-2009 at Tamil Nadu agricultural University, Coimbatore to study the effect of drip fertigation on growth, yield and economics of intensive maize based intercropping system. Drip fertigated maize with 100 per cent recommended dose of fertilizer (RDF) with 50 per cent P and K as water soluble fertilizer recorded significantly higher grain yield followed by 150 per cent RDF. Among the different intercropping systems, radish intercropped with maize registered higher maize grain equivalent yield of 11153 kg ha -1. Drip irrigation saved water upto 43 per cent, besides enhancing the water use efficiency. Higher net returns (Rs. 56858) and B:C ratio (3.24) were obtained under dripfertigation with 150 per cent recommended dose of fertilizer and radish as intercrop.
  • Authors:
    • Groot, J. C. J.
    • Lantinga, E. A.
    • Navarro-Garza, H.
    • Koerkamp-Rabelista, J. Kleine
    • Flores-Sanchez, D.
    • Kropff, M. J.
    • Rossing, W. A. H.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 91
  • Issue: 2
  • Year: 2011
  • Summary: Enhanced utilization of ecological processes for food and feed production as part of the notion of ecological intensification starts from location-specific knowledge of production constraints. A diagnostic systems approach which combined social-economic and production ecological methods at farm and field level was developed and applied to diagnose extent and causes of the perceived low productivity of maize-based smallholder systems in two communities of the Costa Chica in South West Mexico. Social-economic and production ecological surveys were applied and complemented with model-based calculations. The results demonstrated that current nutrient management of crops has promoted nutrition imbalances, resulting in K-and, less surprisingly N-limited production conditions, reflected in low yields of the major crops maize and roselle and low resource use efficiencies. Production on moderate to steep slopes was estimated to result in considerable losses of soil and organic matter. Poor crop production, lack of specific animal fodder production systems and strong dependence on animal grazing within communal areas limited recycling of nutrients through manure. In combination with low prices for the roselle cash crop, farmers are caught in a vicious cycle of cash shortage and resource decline. The production ecological findings complemented farmers opinions by providing more insight in background and extent of livelihood constraints. Changing fertilizer subsidies and rethinking animal fodder production as well as use of communal lands requires targeting both formal and informal governance structures. The methodology has broader applicability in smallholder systems in view of its low demand on capital intensive resources.