• Authors:
    • Moreno, F.
    • Muñoz-Romero, V.
    • López-Bellido, L.
    • López-Bellido, R. J.
    • Melero,S.
    • Murillo, J. M.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 2
  • Year: 2011
  • Summary: Studies of the impacts of the interactions of soil agricultural practices on soil quality could assist with assessment of better management to establish sustainable crop production system. The main objective was to determine the long-term effects of tillage system, crop rotation and N fertilisation on soil total N and organic C (SOC), labile fractions of organic matter (water soluble carbon, WSC, and active carbon, AC), nitrate content, and soil enzymatic activities (dehydrogenase (DHA), beta-glucosidase (Glu) and alkaline phosphatase (AP)) at four different soil depths (0-5, 5-10, 10-30 and 30-50 cm), in a Mediterranean dryland Vertisol in SW Spain. Tillage systems were conventional tillage (CT) and no tillage (NT). Crop rotations were wheat-sunflower (WS), wheat-chickpea (WC), wheat-faba bean (WFb), wheat-fallow (WF) and continuous wheat (WW). Nitrogen fertiliser rates were 0, 50 and 150 kg N ha(-1). The different crop rotation systems had a great influence in soil C and N fractions and enzymatic activities. In general, the SOC. total N. WSC, and beta-glucosidase contents were higher in the no tillage system than in conventional tillage system in the wheat-wheat and in the wheat-faba bean rotations at upper layer (0-5 cm), while the lowest ones were obtained in the wheat-fallow rotation in both tillage systems. Carbon and N fractions, calculated by volumetric soil, showed an increase with depth in both tillage systems and in all crop rotations, which could be related to the increase of soil bulk density and soil mass with depth. The highest N fertiliser rate increased most of soil variables, especially nitrate content at deeper layers, thereby precautions should be taken with long-term N fertilisation to avoid leaching of nitrates below the tillage layer. With the exception of wheat-fallow rotation, slightly greater grain and above-ground biomass yields were obtained for wheat in NT, especially at 150 kg N ha(-1). Combination of NT with any biannual rotation except fallow could be an adequate sustainable management in order to improve soil quality of Vertisols, under our conditions. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Ball, L. O.
    • Vandever, M. W.
    • Milchunas, D. G.
    • Hyberg, S.
  • Source: Rangeland Ecology & Management
  • Volume: 64
  • Issue: 3
  • Year: 2011
  • Summary: The effects of grazing, mowing, and type of cover crop were evaluated in a previous winter wheat fallow cropland seeded to grassland under the Conservation Reserve Program in eastern Colorado. Prior to seeding, the fallow strips were planted to forage sorghum or wheat in alternating strips (cover crops), with no grazing, moderate to heavy grazing, and mowing (grazing treatments) superimposed 4 yr after planting and studied for 3 yr. Plots previously in wheat had more annual and exotic species than sorghum plots. Concomitantly, there were much greater abundances of perennial native grass and all native species in sorghum than wheat cropped areas. The competitive advantage gained by seeded species in sorghum plots resulted in large increases in rhizomatous western wheatgrass. Sorghum is known to be allelopathic and is used in crop agriculture rotations to suppress weeds and increase crop yields, consistent with the responses of weed and desired native species in this study. Grazing treatment had relatively minor effects on basal and canopy cover composition of annual or exotic species versus perennial native grass or native species. Although grazing treatment never was a significant main effect, it occasionally modified cover crop or year effects. Opportunistic grazing reduced exotic cheatgrass by year 3 but also decreased the native palatable western wheatgrass. Mowing was a less effective weed control practice than grazing. Vegetative basal cover and aboveground primary production varied primarily with year. Common management practices for revegetation/restoration currently use herbicides and mowing as weed control practices and restrict grazing in all stages of development. Results suggest that allelopathic cover crop selection and opportunistic grazing can be effective alternative grass establishment and weed control practices. Susceptibility, resistance, and interactions of weed and seeded species to allelopathic cover species/cultivars may be a fruitful area of research.
  • Authors:
    • Stroosnijder, L.
    • Nyakudya, I. W.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 10
  • Year: 2011
  • Summary: Maize ( Zea mays L.), the dominant and staple food crop in Southern and Eastern Africa, is preferred to the drought-tolerant sorghum and pearl millet even in semi-arid areas. In semi-arid areas production of maize is constrained by droughts and poor rainfall distribution. The best way to grow crops in these areas is through irrigation, but limited areal extent, increasing water scarcity, and prohibitive development costs limit the feasibility of irrigation. Therefore, there is need for a policy shift towards other viable options. This paper presents daily rainfall analysis from Rushinga district, a semi-arid location in Northern Zimbabwe. The purpose of the rainfall analysis was to assess opportunities and limitations for rainfed maize production using 25 years of data. Data was analysed using a variety of statistical methods that include trend analysis, t-test for independent samples, rank-based frequency analysis, Spearman's correlation coefficient and Mann-Whitney's U test. The results showed no evidence of change in rainfall pattern. The mean seasonal rainfall was 631 mm with a standard deviation (SD) of 175 mm. December, January and February consistently remained the major rainfall months. The results depicted high inter-annual variability for both annual and seasonal rainfall totals, a high incidence of droughts ≥3 out of every 10 years and ≥1 wet year in 10 years. Using the planting criteria recommended in Zimbabwe, most of the plantings would occur from the third decade of November with the mode being the first decade of December. This predisposes the rainfall to high evaporation and runoff losses especially in December when the crop is still in its initial stage of growth. On average 5 to more than 20 days dry spells occupy 56% of the rainy season. Seasonal rainfall exhibited negative correlation ( P
  • Authors:
    • Odhiambo, J. J. O.
  • Source: African Journal of Agricultural Research
  • Volume: 6
  • Issue: 1
  • Year: 2011
  • Summary: Much of the smallholder farming sector in Limpopo province of South Africa is located on infertile degraded soils, with nitrogen being one of the predominantly deficient nutrient. The use of green manure legume cover crops in combination with Nitrogen (N) fertilizers is one option for improving N inputs into such farming systems. The objectives of this study were to (1) screen a number of green manure legume cover crop species, mucuna (Mucuna pruriens); sunhemp (Crotalaria juncea), lab-lab (Lablab purpureus); cowpea (Vigna unguiculata) and butterfly pea (Clitoria ternatea) in order to determine their suitability for the region and (2) to determine the effect of the green manure and nitrogen fertilizer on maize yield. The legumes were screened during the winter seasons of 2005 and 2006 and the summer seasons of 2005 - 2006 and 2006 - 2007. The best-bet legumes (mucuna, sunhemp and lab-lab) were then evaluated to determine their effect on maize grain yield with or without nitrogen fertilizer. The treatments imposed were mucuna, sunhemp, lab-lab, and a control with (75 kg N ha(-1)) or without (0 kg N ha(-1)) N fertilizer. Maize was harvested at maturity to determine the grain yield. In the screening trials, legume biomass yield ranged between 41 to 1,672 kg ha(-1), while the N content ranged between 2 to 58 kg N ha(-1) in the winter trials. In the summer trials, biomass yield ranged from 899 to 13,586 kg ha(-1), while the N content ranged between 27 to 302 kg N ha(-1). Maize yield ranged between 4.0 to 6.4 tons ha(-1) in the 2006 - 2007 seasons and between 5.8 to 8.4 tons ha(-1) in the 2007 - 2008 season. Control (-N) treatment had the lowest yield in both seasons. Overall, legume treatments, with or without N fertilizers produced between 19 to 58% more grain yield than control (-N). Of the green manure legumes screened, mucuna, lablab and sunhemp seem to be the most suitable green manure legume cover crops for this area and should be planted in the early summer season to maximize biomass production and N accumulation. Use of green manure legumes has the potential to increase maize yield in smallholder farms in Limpopo province.
  • Authors:
    • Pereira, L. G. R.
    • de Oliveira, P. T. L.
    • Voltolini, T. V.
    • Turco, S. H. N.
    • de Araújo, G. G. L.
    • Mistura, C.
    • Menezes, D. R.
  • Source: Revista Ceres
  • Volume: 58
  • Issue: 2
  • Year: 2011
  • Summary: This study was carried out to evaluate the influence of climatic factors on performance and physiological responses of sheep fed on different protein supplements in grazing Tifton 85 ( Cynodon spp.) irrigated in conditions of Brazilian semiarid climate. A total of 28 male Santa Ines * SPRD (undefined breed), castrated lambs, with initial weight of 28 kg, received three different sources of protein in the supplement (soybean meal, cotton cake and urea) and a control treatment, only on grass. The parameters evaluated were: dry matter intake, average daily gain, physiological parameters [respiratory rate (FR), surface temperature (TS) and rectal temperature (TR)] and environmental parameters. Under the climatic conditions imposed by the experiment, the period of the afternoon led the animals to a condition of high heat stress, regardless of the diet. Supplementation affected roughage intake without changing sheep performance, making it economically unfeasible. Protein source derived from cotton cake and used in the supplement for the lambs in grazing increased FR, influencing their thermal comfort.
  • Authors:
    • Woltering, L.
    • Pasternak, D.
    • Nikiema, A.
    • Claude, Z.
    • Ryckewaert, P.
    • Ratnadass, A.
    • Thunes, K.
    • Zakari-Moussa, O.
  • Source: Acta Horticulturae
  • Issue: 917
  • Year: 2011
  • Summary: The agroecological approach to agroecosystem management relies on two pillars: vegetational diversification and soil biological activity enhancement. Although crop pests and their natural enemies may be diversely affected by measures derived from these principles, those generally result in increased agroecosystem resilience vis-a-vis both aerial and soil pests. Earlier studies by ICRISAT and CIRAD and their partners in West Africa showed the potential of the implementation of these principles for the management of some major pests of both staple food and horticultural crops, and their limitations for others, notably in the water-saving and income-generating systems mixing cereals, legumes, and high-value crops currently promoted in the Sudano-Sahelian zones, such as the drip irrigation-based African Market Garden (AMG) and the water harvesting-based Bio-Reclamation of Degraded Lands (BDL) systems. Pigeon-pea showed potential for trap-cropping tomato fruit worm (TFW) on okra, while Andropogon grass was dismissed for such management of stem-borer on pearl millet, and mixed results were obtained with castor bean and other potential trap crops for panicle-feeding bug management on sorghum. The results presented highlight the potential for mobilizing either aerial or soil-bound biological processes for managing fruit flies (FF), the main pest of grafted jujube tree, and leaf worm, the main pest of the Moringa tree, for sustainable production of these two major crops (in BDL and AMG systems, respectively), without having to rely on synthetic pesticide sprays. Studies on the social acceptability of the proposed management options (e.g., pigeon-pea in okra-based BDL) are also underway. The potential of the Jatropha shrub grown as a live-fence around these systems, either for its top-down effects or via the use of its extracts in an assisted push-pull strategy, is discussed. These studies on targeted pathosystems serve the dual purpose of finding solutions to local problems and contribute more globally to the design of pest resilient agrosystems.
  • Authors:
    • Fahandezh-Saadi, S.
    • Sepaskhah, A. R.
    • Zand-Parsa, S.
  • Source: Agricultural Water Management
  • Volume: 99
  • Issue: 1
  • Year: 2011
  • Summary: Simulation of crop yield allows better planning and efficient management under different environmental inputs such as water and nitrogen application. However, most of the models are complicated and difficult to understand. Furthermore, input data are not readily available. The objectives of this investigation were to use logistic equation to quantify the influence of seasonal water and nitrogen application on maize biomass accumulation and grain yield and to develop empirical models for prediction of maize biomass and grain yield. Logistic equations were fitted to dray matter (DM) yield at different times in the growing season at different irrigation water and nitrogen levels. The parameters of the logistic equations were then fitted to irrigation water and nitrogen as empirical functions. Further, the harvest index (HI) was related to the applied water and nitrogen as another empirical model. The empirical logistic models were used to estimate the DM and grain yield based on data from another experiment in the same area. Results indicated that the empirical models predicted the DM yield during the growing season with an acceptable accuracy, but dry matter (DM) prediction at harvest was very good. The grain yield also was predicted with a very good accuracy. It is concluded that logistic equation along with the presented empirical models for prediction of constants in logistic equation and HI are appropriate for accurate prediction of DM and grain yield of maize at the study region.
  • Authors:
    • Kabenge, I.
    • Irmak, S.
    • Sharma, V.
    • Kilic, A.
  • Source: Transactions of the ASABE
  • Volume: 54
  • Issue: 3
  • Year: 2011
  • Summary: Understanding the relationship between the spatial distribution of precipitation and crop yields on large scales (i.e., county, state, regional) while accounting for the spatial non-stationarity can help managers to better evaluate the long-term trends in agricultural productivity to make better assessments in food security, policy decisions, resource assessments, land and water resources enhancement, and management decisions. A relatively new technique, geographically weighted regression (GWR), has the ability to account for spatial non-stationarity with space. While its application is growing in other scientific disciplines (i.e., social sciences), the application of this new technique in agricultural settings has not been practiced. The geographic information system (GIS), along with two different statistical techniques [GWR and conventional ordinary least square regression (OLS)], was utilized to analyze the relationships between various precipitation categories and irrigated and rainfed maize and soybean yields for all 93 counties in Nebraska from 1996 to 2008. Precipitation was spatially interpolated in ArcGIS using a spline interpolation technique with zonal statistics. Both measured and GWR- and OLS-predicted yields were correlated to spatially interpolated annual (January 1 to December 31), seasonal (May 1 to September 30), and monthly (May, June, July, August, and September) precipitation for each county. Statewide average annual precipitation in Nebraska from 1996 to 2008 was 564 mm, with a maximum of 762 mm and minimum of 300 mm. Mean precipitation decreased gradually from May to September during the growing season. County average yields followed the same temporal trends as precipitation. When the OLS regression model was used, there was a general trend of linear correlation between observed yield and long-term average mean annual total precipitation with a varying coefficient of determination (R 2). For rainfed crops, 67% of the variability in mean yield was explained by the mean annual precipitation. About 23% and 17% of the variability in mean yield was explained by mean annual precipitation for irrigated maize and soybean, respectively. However, the performance of the GWR technique in predicting the yields from spatially interpolated precipitation for irrigated and rainfed maize and soybean was significantly better than the performance of the OLS model. For both rainfed maize and soybean, 77% to 80% of the variation in yield was explained by the mean annual precipitation alone. For irrigated crops, 42% of the variation in the yield was explained by the mean annual precipitation. For rainfed crops, there was a strong correlation between seasonal precipitation and yield, with R 2 values of 0.73 and 0.76 for maize and soybean, respectively. The mean annual total precipitation was a better predictor of rainfed maize yield than rainfed soybean yield. On a statewide average, July precipitation as a predictor had the greatest correlation with yields of both maize and soybean. June, July, and August precipitation had greater impact on maize yield than on soybean under rainfed conditions due to more sensitivity of maize to water stress than soybean. For irrigated yields, July precipitation had more impact on soybean yield than on maize. The performance of the GWR technique was superior to the OLS model in analyzing the relationship between yield and precipitation. The superiority of the GWR technique to OLS is mainly due to its ability to account for the impact of spatial non-stationarity on the precipitation vs. yield relationships.
  • Authors:
    • Sediyama, G. C.
    • Moura, M. S. B. de
    • Souza, L. S. B. de
    • Silva, T. G. F. da
  • Source: Bragantia
  • Volume: 70
  • Issue: 3
  • Year: 2011
  • Summary: This study aimed to analyze the productivity, the water use efficiency, and the economical viability for corn and cowpea crops on single and intercropping systems in the Brazilian semiarid region. The experiment was carried out at Petrolina, State of Pernambuco. The crops, in different planting systems (single and intercropping), underwent the five blades of irrigation, applied at the flowering stage of cowpea to 40 days after sowing. Combining the settings of cultivation system and the different depths of irrigation, crops of maize and cowpea were subjected to 15 different treatments. To evaluate the performance of crops in the different treatments indicators that consider the production response of crops and the performance of the application of water in the production system were used. The grain yield responses of maize and cowpea to the soil water content were reduced in intercropped plantations, in relation to single cropping. Even so, in economic terms, the adoption of maize-cowpea proved to be more advantageous in all treatments.
  • Authors:
    • Tadesse, T.
    • Narumalani, S.
    • Wardlow, B. D.
    • Swain, S.
    • Callahan, K.
  • Source: GIScience & Remote Sensing
  • Volume: 48
  • Issue: 3
  • Year: 2011
  • Summary: Eight-day composite Terra-MODIS cumulative LST and NDVI timeseries data were used to analyze the responses of crop and grassland cover types to drought in Nebraska. Four hundred ninety 1 km pixels that included irrigated and non-irrigated corn and soybeans and three grassland cover types were selected across the state of Nebraska. Statistical analyses revealed that the majority of the land cover pixels experienced significantly higher daytime and nighttime LSTs and lower NDVI during the drought-year growing season ( p