• 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:
    • Smith, P.
    • Hillier, J.
    • Walter, C.
    • Malin, D.
    • Garcia-Suarez, T.
    • Mila-i-Canals, L.
  • Source: Environmental Modelling & Software
  • Volume: 26
  • Issue: 9
  • Year: 2011
  • Summary: Agriculture and deforestation contribute approximately one third of global greenhouse gas emissions. Major sources of emissions in this sector are from loss of soil carbon due to repeated soil disturbance under typical crop cultivation, fossil fuel use in the production of synthetic fertilisers, direct and indirect soil nitrous oxide emissions from fertiliser application, pesticide manufacture and use, and fossil fuel combustion in machinery use (e.g. tractors, irrigation, etc). Although knowledge of emissions sources aids in the determination of potential mitigation strategies (reduced or no-till methods, use of N-fixing leguminous crops in rotations, use of lower emissions fertilisers), there currently exist limited decision support and knowledge transfer tools to enable the farmer or grower to make choices appropriate to existing management practices. In this article we present a model, and open source software tool called the "Cool Farm Tool" integrating several globally determined empirical models in a greenhouse gas calculator. The software, in requiring inputs of which a farmer typically has good knowledge (and no more), has a specific farm-scale, decision-support focus. Due to its use of only readily available farm data, there is considerable scope for its use in global surveys to inform on current practices and potential for mitigation.
  • Authors:
    • Lavee, S.
  • Source: Acta Horticulturae 888: International Symposium on Olive Irrigation and Oil Quality
  • Issue: 888
  • Year: 2011
  • Summary: The olive commodity spread in ancient times hand in hand with western civilization in the Mediterranean basin. It was till recently and in many regions still is a highly traditionally cultivated commodity. Table olives were subjected about 200 years ago to irrigation and intensification. This was unacceptable in olive cultivation for oil extraction. During the last century the economy of the olive industry declined and became questionable. A drastic increase in efficiency of the olive oil industry was obligatory for its survival. In the nineteen fifties, an approach to intensify the olive oil industry was initiated using irrigation and modern nutrition. The initial results indicated a significant increase in production without reducing oil quality. Slight changes in taste occurred occasionally due to quantitative changes of some oil constituents but oil quality was not affected. Some of these oils gained high prizes in international competitions. Some cultivars responded to irrigation better than others regarding growth, fruit yield and relative oil content. Thus, selection and breeding of responsive cultivars to intensification was initiated. Once responsive cultivars were identified and planted commercially in pioneering orchards, a revolution of the olive oil industry was initiated. An increase in both fruit and oil yield up to more than five times that in traditional orchards was achieved. This increased production and tree uniformity initiated the development of new orchard systems, advanced mechanization and oil mill technologies reducing manual labor. This attracted large scale orchard development in traditional, new and marginal regions. Basis on this development it can be concluded that the introduction of irrigation revolutionized the world's olive oil industry from a traditional barely economic one to a thriving modern economical developing industry.
  • Authors:
    • Nakayama, T.
  • Source: Agricultural and Forest Meteorology
  • Volume: 151
  • Issue: 3
  • Year: 2011
  • Summary: To account for complex and diverse water system involving river dry-up, groundwater degradation, agricultural/urban water use, and dam/canal effects in heavily irrigated Yellow River Basin, this study coupled NIES Integrated Catchment-based Eco-hydrology (NICE) model series with more complex sub-models involving various factors (NICE-DRY). The model reproduced reasonably evapotranspiration, irrigation water use, groundwater level, and river discharge during spring/winter wheat, summer maize, and summer rice cultivations. Scenario analysis predicted the impact of irrigation on both surface water and groundwater, which had previously been difficult to evaluate. The simulated discharge with irrigation was improved in terms of mean value, standard deviation, and coefficient of variation. Another scenario analysis of conversion from dryland to irrigated fields predicted that the effect of groundwater irrigation was predominant in the middle and downstream and the resultant groundwater degradation predominantly, where surface water was seriously limited. Simulated dry biomasses of wheat and maize were linearly related to Time-Integrated Normalized Difference Vegetation Index (TINDVI) estimated from satellite images. Temporal gradient of TINDVI during 1982-1999 showed spatially heterogeneous distribution and increasing trends in the wheat and maize fields, indicating that the production increases were related to irrigation water and the resultant hydrologic changes. This integrated approach could help to estimate a close relationship between crop production, hydrologic cycle, and water availability, and predict heterogeneous vulnerability of water resources. Because this region experienced substantial river dry-up and groundwater degradation at the end of the 20th century, this approach would help to overcome substantial pressures of increasing food demand and declining water availability, and to decide on appropriate measures for whole water resources management to achieve sustainable development under sound socio-economic conditions.
  • Authors:
    • Buzetti, S.
    • Bergamaschine, A. F.
    • Ulian, N. de A.
    • Pariz, C. M.
    • Furlan, L. C.
    • Andreotti, M.
    • Meirelles, P. R. de L.
    • Cavasano, F. A.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: The greatest limitation to the sustainability of no-till systems in Cerrado environments is the low quantity and rapid decomposition of straw left on the soil surface between fall and spring, due to water deficit and high temperatures. In the 2008/2009 growing season, in an area under center pivot irrigation in Selviria, State of Mato Grosso do Sul, Brazil, this study evaluated the lignin/total N ratio of grass dry matter, and N, P and K deposition on the soil surface and decomposition of straw of Panicum maximum cv. Tanzania, P. maximum cv. Mombaca, Brachiaria brizantha cv. Marandu and B. ruziziensis, and the influence of N fertilization in winter/spring grown intercropped with maize, on a dystroferric Red Latosol (Oxisol). The experiment was arranged in a randomized block design in split-plots; the plots were represented by eight maize intercropping systems with grasses (sown together with maize or at the time of N side dressing). Subplots consisted of N rates (0, 200, 400 and 800 kg ha -1 year -1) sidedressed as urea (rates split in four applications at harvests in winter/spring), as well as evaluation of the straw decomposition time by the litter bag method (15, 30, 60, 90, 120, and 180 days after straw chopping). Nitrogen fertilization in winter/spring of P. maximum cv. Tanzania, P. maximum cv. Mombaca, B. brizantha cv. Marandu and B. ruziziensis after intercropping with irrigated maize in an integrated crop-livestock system under no-tillage proved to be a technically feasible alternative to increase the input of straw and N, P and K left on the soil surface, required for the sustainability of the system, since the low lignin/N ratio of straw combined with high temperatures accelerated straw decomposition, reaching approximately 30% of the initial amount, 90 days after straw chopping.
  • Authors:
    • Sarker, S. C.
    • Patra, P. S.
    • Mula, G.
    • Paramanik, B.
  • Source: Journal of Crop and Weed
  • Volume: 7
  • Issue: 1
  • Year: 2011
  • Summary: Zero tillage saves tillage and irrigation costs, results in yield gains through a possible improvement in sowing time and enhanced fertilizer and water use efficiencies. The present study was conducted to explore the possibilities of saving critical inputs and to enhance the profit margin of the rural farmers of Uttar Dinajpur, Dakshin Dinajpur, Malda and Murshidabad districts of West Bengal through National Agricultural Innovation Project. Mean grain yield of 10 villages showed that zero tillage practices produced 8.004% more grain yield than conventional tillage method. On an average zero tillage method save total cost of Rs. 4449.67 ha -1 and increase profit margin of Rs. 7056.25 ha -1. Zero till field also recorded higher B:C ratio of 0.923 as compared to conventional tillage method (0.432).
  • Authors:
    • Schindler, U.
    • Muller, L.
  • Source: AMA-Agricultural Mechanization in Asia, Africa and Latin America
  • Volume: 42
  • Issue: 4
  • Year: 2011
  • Summary: Efficient water use and intelligent water management are essential for sustainable agricultural production. Long-term soil hydrological measurements were used to quantify deep drainage rates and nitrate losses from arable land managed under various farming regimes (integrated, integrated with irrigation, ecologic and low input) and tillage systems (plough and no till) in the Pleistocene region of Northeast Germany from 1994 to 2007. As dependent on the management system, the nitrate concentration varied between 40 and 150 mg l -1. In connection with annual deep drainage rates between 100 mm and 200 mm during the study period, the annual nitrogen loss varied between 14 and 41 kg ha -1. Differences in nitrogen loss observed between the farming systems were low, but yields increased and nitrogen losses decreased as a result of irrigation throughout the variants. No-till treatment resulted in reduced nitrate leaching (18 kg ha -1) as compared with the tillage systems with plough and tooth cultivator (27 kg ha -1).
  • Authors:
    • Carvalho, D.
    • Pereira, J.
    • Silva, L.
    • Guerra, J.
    • Souza, A.
  • Source: ACTA SCIENTIARUM-AGRONOMY
  • Volume: 33
  • Issue: 1
  • Year: 2011
  • Summary: The objective of this study was to determine the crop evapotranspiration (ETc), crop coefficients (kc) and water-use efficiency (EUA) of the bell pepper crop in the no till system (PD) and conventional tillage system (PC), in the Fluminense Valley, Rio de Janeiro State, Brazil. The irrigation was managed and the evapotranspiration demand quantified by calculating the daily soil water balance using the TDR technique and data collected in an automatic meteorological station. It was verified that the accumulated ETc at 181 days after planting (DAT) was 363 and 335 mm for PD and PC, respectively. The kcs obtained were 0.32, 1.18 and 0.77 and 0.34, 1.05 and 0.86, for the PD and PC systems, respectively, in the initial (0-40 DAP), middle (81-120 DAP) and final (181 DAP) growth phases, respectively. The kc values for the bell pepper crop presented by FAO were similar to the values found for the PC, but are not recommended for PD. Considering the total depth applied (rain and irrigation), the average values of water use efficiency were 3.9 and 4.5 kg m -3 for PD and PC, respectively.
  • Authors:
    • Sa, M.
    • Arf, O.
    • Buzetti,S.
    • Andreotti, M.
    • Teixeira Filho, M.
    • Souza, J.
  • Source: Bragantia
  • Volume: 70
  • Issue: 2
  • Year: 2011
  • Summary: The second corn crop is an important economical alternative for agriculture. As this crop removes great amounts of N, it is necessary an appropriate nitrogen fertilization management for obtaining high yields. The objective of this work was to evaluate the effect of sources, doses and times of nitrogen application on agronomic characteristics and productivity of corn grains in an irrigated second crop. The experiment was accomplished in Selviria, Mato Grosso do Sul State, in a red dystrophic Latosol irrigated by sprinkle and conducted under no till, in 2007 and 2008. The experiment was arranged in randomized complete blocks design, with 4 repetitions, disposed in a factorial scheme 5*3*2, being: five doses of N (0, 50, 100, 150 and 200 kg ha -1), three sources of N (ammonium sulfonitrate with nitrification inhibitor, ammonium sulfate and urea) applied at sowing or totally at sidedressing in the stage of 6 leaves. The N sources provided similar grain yield. The nitrogen application at sowing was viable, as well as the traditional application of N at sidedressing. The increment of N doses increased the leaf N content, the number of grains per line and per ear and consequently the grain yield. The N doses increased the grain yield of the second crop up to 150 kg ha -1 of N, independently of application time or N sources.
  • Authors:
    • Arf, O.
    • Sa, M.
    • Andreotti, M.
    • Buzetti, S.
    • Teixeira Filho, M.
  • Source: Ciencia Rural
  • Volume: 41
  • Issue: 8
  • Year: 2011
  • Summary: Proper management of nitrogen fertilization and using cultivars with high productive potential are essential to obtain high wheat yield. Thus, the objective of the present study was to assess the effects of different N doses and sources, one with a nitrification inhibitor, applied at sowing or as side dressing, on the production components and yield of two wheat cultivars irrigated, under no till, cultivated in a region of low altitude Cerrado (Selviria - MS). A randomized block design was used in a 5*3*2*2 factorial arrangement, that is, five nitrogen doses (0, 50, 100, 150 and 200 kg ha -1), three nitrogen sources (ammonium sulfonitrate with nitrification inhibitor (Entec), ammonium sulfate and urea) and two nitrogen application times (at sowing or side dressing) on two wheat cultivars ('E 22' and 'E 42') with three replications. There was no difference for grain yield between the wheat cultivars and among the nitrogen sources. The application of nitrogen totally at sowing is feasible as well as the traditional application at sowing and side dressing. The nitrogen doses increased the leaf N content of the 'E 22' cultivar, resulting in a reduction in the hectolitric mass of the 'E 42' cultivar and increased grain yield of the 'E 22' and 'E 42' wheat yield cultivars, respectively, up to doses of 126 and 122 kg ha -1 N, regardless of the application time and the nitrogen source.