• Authors:
    • Liu, S.
    • Jiang, S.
    • Liu, S.
    • Hu, W.
    • Wan, S.
    • Kang, Y.
    • Wang, R.
  • Source: Agricultural Water Management
  • Volume: 110
  • Year: 2012
  • Summary: In order to evaluate the effects of different amounts of water, applied by drip irrigation, to a saline-sodic soil (surface ECe > 40 dS/m; SAR > 40), on cotton growth and soil salinity, a three-year experiment was conducted on a saline wasteland in Xinjiang Northwest China during 2008-2010. Five water treatments were used for this experiment based on the soil-water matric potential (SMP) measured 20 cm beneath a drip emitter located close to the plant: the SMP levels used to determine when to irrigate were -5 kPa (S1), -10 kPa (S2). -15 kPa (S3), -20 kPa (S4), and -25 kPa (S5). After three years, both the soil salinity (ECe) and sodicity (SAR) declined significantly in 0-120 cm depth and more reduction were achieved in 0-40 cm soil depth than in 40-80 and 80-120 cm depths. Moreover, the reductions of SAR were smaller than those of ECe. Additionally, the amount of salt removed from the 0 to 80 cm depth decreased with decreasing SMP threshold. The S1 treatment resulted in the highest lint yields in 2009 and 2010. Considering the effects of leached salts on the environment of deep soil layer and the yield of cotton, an SMP of -10 kPa can be used to trigger irrigation for cotton in the first three years for saline wasteland reclamation in Xinjiang Northwest China. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.
  • Authors:
    • Vazin, F.
    • Abbasi, M.
  • Source: Advances in Environmental Biology
  • Volume: 6
  • Issue: 4
  • Year: 2012
  • Summary: In most areas of Isfahan Province, the maize is cultivated as a second crop after harvesting the wheat or barely and the farmers of this region are confronting with time-limit problems in performing correct yield of providing the soil bed, and the tillage is an expensive and energy-consuming yield. Thus, for examining the effect of tillage on the elimination of mechanical yield and saving the time and the expense of performing yield as well as the effect of appropriate date for planting the maize on the performance and its components, an experiment is conducted as a split plot design, 4 times in the agricultural year 2010 in Mourchekhort area of Isfahan. The factors including tillage in two levels (Current Tillage "CT" and Non-tillage "NT") on the main plot and the planting date in three levels (29 th June-15 th July-28 th July) with 15-day interval on the secondary plot were operated on the maize sort No. I704. The tillage system is not significantly effective on the biological performance. In tillage system, the performance of the grain, the number of corns in the maize row and the total number of corn in the maize showed respectively 10%, 12% and 22% increases, compared to those in nontillage system. On 29 th June, the weight of one-thousand corns was decreased 13% and the performance of the corn, the number of corns in the maize row and the total number of corns in the maize was respectively increased in 35%, 16% and 30% compared to those on 29 th July. Reciprocal effect of tillage system and planting dates didn't effect on the corn's performance and its components. Considering the results achieved, the best planting date for both tillage systems in this area is 29 th June.
  • Authors:
    • Dercon, G.
    • Kumar S.
    • Garg, A. K.
    • Manchanda, J. S.
    • Aulakh, M. S.
    • Nguyen, M. L.
  • Source: Soil & Tillage Research
  • Volume: 120
  • Year: 2012
  • Summary: Continuing cereal-based crop rotations such as rice-wheat, intensive cultivation and complete removal of postharvest crop residue (CR) for animal consumption and fuel, or its burning have reduced the organic matter content and productivity of irrigated semi-arid subtropical soils of South Asia. Identification of effective strategies for the management of tillage and CR could foster sustainable and environmentally sound agricultural systems. To this effect, a 4-year field experiment was established with annual soybean-wheat rotation under subtropical climate conditions in the Indo-Gangetic Plains of Northwestern India to evaluate the integrated effects of tillage, CR retainment, mineral fertilizers and farmyard manure (FYM) on crop production, nutrients uptake, soil moisture storage and temperature dynamics. The experimental soil was loamy sand, poor in organic C and low in available P. Sixteen treatment combinations involved recommended and 25% higher NP rates without or with 10 t FYM ha -1 and CR incorporated in conventional tillage (CT) and retained on the soil surface in conservation agriculture (CA) system. The results clearly revealed that (a) soybean yield was 2-6% higher in CA than CT in different treatments with and without CR, (b) significantly higher uptake of N and P by soybean from CR-amended treatments of both CT and CA, which reflected its effect in improving the soybean yield, (c) the current fertilizer NP recommendation of 20 kg N and 26 kg P ha -1 for soybean is not adequate and either application of 25% higher NP rate (25 kg N and 33 kg P ha -1) or additional 10 t FYM ha -1 is required for optimum crop production of ~2500 kg ha -1, (d) CA conserved more water in soil profile than CT, however, the differences in soil moisture storage in CT vis-a-vis CA were not reflected in soybean yield presumably due to frequent wetting of soil by heavy monsoonal rains, (e) the wheat yield was highest in both CT and CA systems when grown with the application of 150 kg N and 33 kg P ha -1 without CR and was 7% higher in CA (4140 kg ha -1) than CT (4048 kg ha -1), and (f) retention of CR on soil surface in winter-grown wheat under CA reduced wheat yield by 8-24% and N uptake by 3-5% as a consequence of mulching effects creating cooler environment in surface soil layer during initial 3 weeks after seeding, which led to the delayed germination and relatively poor crop growth during initial period.
  • 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:
    • 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:
    • Li, W.
    • He, R.
  • Source: Journal of Yunnan Agricultural University
  • Volume: 26
  • Issue: 4
  • Year: 2011
  • Summary: Jianghuai region is one of the major grain producing areas in China, where planting has high energy consumption. In addition, greenhouse gases displacement of planting is larger than ever, and the phenomenon of straw burned is extremely serious. To solve the problem, the multifunctional no-till wheat and paddy planter was designed with the technique of mechanized cultivation of energy-saving emission reduction. Combing with controlled traffic tillage and strip chopping anti-blocking mechanism, it could be used to returning corn stalks to the filed, fertilizing, seeding, covering and so on. The filed experiment indicates that the machine can decrease operating power consumption, and its steering ability is outstanding.
  • Authors:
    • Miyamoto, S.
    • Nesbitt, M.
  • Source: HortTechnology
  • Volume: 21
  • Issue: 5
  • Year: 2011
  • Summary: Soil salinity management is a factor for successful production of pecan ( Carya illinoinensis) in arid southwestern United States. An exploratory study was performed to evaluate the effect of various soil management practices on salt leaching in basin-irrigated orchards developed on alluvial soils (Torrifluvents, Entisols) of the middle Rio Grande Basin. The practices evaluated were ripping, minimum-till chiseling, and soil profile modification. For ripping, parabolic shanks were passed through the center section (4 to 8 ft wide) between each tree row to a depth ranging from 18 to 36 inches. Minimum-till chisels included 7- and 30-inch shanks, equipped with coulters to reduce break up of the ground surface. Soil profile modification consisted of trenching with a backhoe and profile mixing with a large excavator. The effectiveness of these methods was evaluated by measuring soil salinity and moisture in treated and untreated zones at 17 test sites. Both ripping and minimum-till deep chiseling helped improve salt leaching, and the effectiveness of salt leaching increased as working depths approach the thickness of the clayey layer. However, annual ripping of the center section of each tree row space may not provide wide enough zones to alleviate salt stress to the trees. Straight shanks prune but do not lift tree roots, thus appearing to be better suited for chiseling closer to tree rows. Soil profile modification was highly effective in leaching salts. From the view of minimizing soil aggregate destruction and of maintaining a leveled floor, minimum-till deep chiseling, followed by the use of sand-topdressing and minimum-till shallow chisels for maintenance may prove to be more desirable than conventional ripping, especially in soil types consisting of silty clay loam.
  • Authors:
    • Mupangwa, W.
    • Jewitt, G. P. W.
  • Source: Physics and Chemistry of the Earth, Parts A/B/C
  • Volume: 36
  • Issue: 14-15
  • Year: 2011
  • Summary: Crop output from the smallholder farming sector in sub-Saharan Africa is trailing population growth leading to widespread household food insecurity. It is therefore imperative that crop production in semi-arid areas be improved in order to meet the food demand of the ever increasing human population. No-till farming practices have the potential to increase crop productivity in smallholder production systems of sub-Saharan Africa, but rarely do because of the constraints experienced by these farmers. One of the most significant of these is the consumption of mulch by livestock. In the absence of long term on-farm assessment of the no-till system under smallholder conditions, simulation modelling is a tool that provides an insight into the potential benefits and can highlight shortcomings of the system under existing soil, climatic and socio-economic conditions. Thus, this study was designed to better understand the long term impact of no-till system without mulch cover on field water fluxes and maize productivity under a highly variable rainfall pattern typical of semi-arid South Africa. The simulated on-farm experiment consisted of two tillage treatments namely oxen-drawn conventional ploughing (CT) and ripping (NT). The APSIM model was applied for a 95 year period after first being calibrated and validated using measured runoff and maize yield data. The predicted results showed significantly higher surface runoff from the conventional system compared to the no-till system. Predicted deep drainage losses were higher from the NT system compared to the CT system regardless of the rainfall pattern. However, the APSIM model predicted 62% of the annual rainfall being lost through soil evaporation from both tillage systems. The predicted yields from the two systems were within 50 kg ha(-1) difference in 74% of the years used in the simulation. In only 9% of the years, the model predicted higher grain yield in the NT system compared to the CT system. It is suggested that NT systems may have great potential for reducing surface runoff from smallholder fields and that the NT systems may have potential to recharge groundwater resources through increased deep drainage. However, it was also noted that the APSIM model has major shortcomings in simulating the water balance at this level of detail and that the findings need to be confirmed by further field based and modelling studies. Nevertheless, it is clear that without mulch or a cover crop, the continued high soil evaporation and correspondingly low crop yields suggest that there is little benefit to farmers adopting NT systems in semiarid environments, despite potential water resources benefits downstream. In such cases, the potential for payment for ecosystem services should be explored.
  • Authors:
    • Benkherbache, N.
    • Rahali, A.
    • Makhlouf, M.
  • Source: Options Mediterraneennes. Serie A, Seminaires Mediterraneens
  • Issue: 96
  • Year: 2011
  • Summary: The objective of the experiment was to study the development of weed in the durum wheat grown under three cropping techniques, conventional, minimum and no till, after two years of implementation, in the semi arid zone of Setif. Weed seed bank has been estimated in the 0-15 and 15-30 cm soil profile as well as surface weed density. Nineteen species were identified, with a predominance of Polygonum aviculare L., Veronica hederifolia L., Chenopodium vulvaria L. and Avena sterilis. Other species, not less important, are annual dicotyledonous largely known in the region, among which Fumaria densiflora, Fumaria officinalis, Sonchus arvensis L., Papaver rhoeas L., Daucus carota L. and Bifora radiens. Monocotyledons dominated under no till with an average plant density of 57.3 plants/m 2 while the dicotyledonous dominated under shallow tillage with an average plant density of 70.5 plants/m 2. Conventional tillage was characterized by equilibrium between both weed families.
  • Authors:
    • Corbeels, M.
    • Rufino, M. C.
    • Nyamangara, J.
    • Giller, K. E.
    • Rusinamhodzi, L.
    • van Wijk, M. T.
  • Source: Agronomy for Sustainable Development
  • Volume: 31
  • Issue: 4
  • Year: 2011
  • Summary: Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact.