• Authors:
    • Rocha, H. S.
    • Souza, A. P. de
    • Carvalho, D. F. de
    • Lima, M. E. de
    • Guerra, J. G. M.
  • Source: Revista Brasileira de Engenharia Agrícola e Ambiental
  • Volume: 16
  • Issue: 6
  • Year: 2012
  • Summary: This study was carried out in the municipality of Seropedica-RJ, in order to determine, under organic farming and no tillage system, the yield of eggplants under different irrigation depths and cropping systems (intercropped with legumes and alone). The experimental design was in randomized blocks in a split plot design with four replications. The plots were characterized by the treatments corresponding to different water depths (40, 70, 100, 120% ETc), and the sub plots, the intercropping systems with cowpea and eggplant alone. Cropping systems did not influence the final yield of eggplant. However, considering the different irrigation depths, the highest commercial yield (65.41 Mg ha -1) was obtained for a total depth of 690.04 mm (106.8% ETc). The lower applied depth provided lower quality of fruit compared with that observed in the higher depths. The rate of fruit discard was 3 and 14%, respectively, for the higher and lower depths of irrigation.
  • Authors:
    • Darshana
    • Pandey, A.
    • Pandey, R. P.
    • Ostrowski, M.
  • Source: Irrigation and Drainage
  • Volume: 61
  • Issue: 2
  • Year: 2012
  • Summary: In this study, simulation and optimization models were assembled for the optimization of irrigation systems and their operation. The simulation model CROPWAT was used for estimation of the crop water requirement, time and depth. The evolutionary algorithm (GANetXL) was used for the optimal planning of cropping pattern, maximization of net benefits and minimization of irrigation water requirements for the study area of Holeta catchment, Ethiopia. The study area encompasses three command areas, i.e. farm A, farm B and Tsedey State Farm, and five different type of crops, i.e. potato, tomato, apple, peach and winter wheat. The simulation results of the CROPWAT model illustrated that crop water requirement for apple was highest (993 mm), followed by peach (908 mm), tomato (470 mm), potato (443 mm) and wheat (294 mm). The study reveals that fruit crops have more crop water requirements than cereals. The results of the GANetXL show that when the cropped area and water allocated was varied between extreme values, 23% of water can be saved. The total benefit from the study area can be enhanced by USD 34 ha -1 and can be helpful in improving the economic conditions of the farmers.
  • Authors:
    • Kabir, M. J.
    • Islam, M. M.
  • Source: Bangladesh Journal of Agricultural Research
  • Volume: 37
  • Issue: 1
  • Year: 2012
  • Summary: The study area was Shanuhar village of Babugonj Upazila of Barisal district, which was selected purposively based on agronomic suitability of growing Rabi crops. Necessary data were collected through focus group discussion (FGD) with 30 farmers including small, medium, and large farm households, school teachers, village leaders all the remaining by using pre design check list and structure schedule during May 2007 considering Rabi season of 2006-2007. Usually, farmers of the village could not sow their crops within the optimum time. They transplanted Aman rice in late due to inundation of land and planting of Rabi crops in late because of land unsuitability and long duration of T. Aman rice. Boro rice was adopted about 75% of the cropped area in Rabi season and but yield was low because of inadequate irrigation facilities. In contrast wheat needs comparatively less irrigation than Boro rice. Moreover, mungbean, mustard, lentil and grass pea produce reasonability good yield in rainfed condition. About 20-25% land become suitable for seeding wheat by first week of December after harvesting NfV T. Aman which indicated good prospect of growing wheat in the study village. Wheat is a more profitable Rabi crop than other crops like grass pea, mustard, lentil. Farmers earned the highest per hectare gross return (Tk.98646) and gross margin (Tk.22870) from the Wheat - Aus rice - T. Aman rice pattern whereas Boro rice - Fallow - T. Aman pattern produced the lowest gross return (Tk.65918) and gross margin (Tk.10134). Higher benefit was achieved from the pattern Wheat - Aus rice - T. Aman rice because of less production cost and high price of wheat grain, though three cereals crops could exhaust soil nutrient so that Mungbean-Aus rice - T. Aman pattern may be alternate option to sustain soil health as well as productivity of the selected area.
  • Authors:
    • Van Remortel, R.
    • Smith, E.
    • Mehaffey, M.
  • Source: Ecological Applications
  • Volume: 22
  • Issue: 1
  • Year: 2012
  • Summary: Meeting future biofuel targets set by the 2007 Energy Independence and Security Act (EISA) will require a substantial increase in production of corn. The Midwest, which has the highest overall crop production capacity, is likely to bear the brunt of the biofuel-driven changes. In this paper, we set forth a method for developing a possible future landscape and evaluate changes in practices and production between base year (BY) 2001 and biofuel target (BT) 2020. In our BT 2020 Midwest landscape, a total of 25 million acres (1 acre = 0.40 ha) of farmland was converted from rotational cropping to continuous corn. Several states across the Midwest had watersheds where continuous corn planting increased by more than 50%. The output from the Center for Agriculture and Rural Development (CARD) econometric model predicted that corn grain production would double. In our study we were able to get within 2% of this expected corn production. The greatest increases in corn production were in the Corn Belt as a result of conversion to continuous corn planting. In addition to changes to cropping practices as a result of biofuel initiatives we also found that urban growth would result in a loss of over 7 million acres of productive farmland by 2020. We demonstrate a method which successfully combines economic model output with gridded land cover data to create a spatially explicit detailed classification of the landscape across the Midwest. Understanding where changes are likely to take place on the landscape will enable the evaluation of trade-offs between economic benefits and ecosystem services allowing proactive conservation and sustainable production for human well-being into the future.
  • Authors:
    • Rodrigues, J. G. L.
    • Fernandes, D. M.
    • Bicudo, S. J.
    • Nascimento, F. M.
    • Fernandes, J. C.
    • Furtado, M. B.
  • Source: Científica (Jaboticabal)
  • Volume: 40
  • Issue: 1
  • Year: 2012
  • Summary: The objective of this research work was to evaluate the effects of doses and time of application of N on the C/N ratio of the straw cover and on the growth and productivity of maize plants growing in a no tillage system. The experiment was carried out at the Experimental Farm of the College of Agriculture of the Sao Paulo State University (UNESP) on its campus of Botucatu, state of Sao Paulo, Brazil. The treatments were distributed in the field according to a randomized complete block design in a split plot arrangement. The treatments consisted of four doses of N (0, 20, 40, and 60 kg ha -1) applied to oat crop and N doses (60, 80, 100, and 120 kg ha -1) sidedressed to corn. The development and productivity of the maize crop in a no-tillage system were found to be dependent of the C/N ratio and the straw cover. The response of the maize plants to the early application of N is dependent on doses and time of application.
  • Authors:
    • Mkwinda, S.
    • Aune,J. B.
    • Ngwira, A. R.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: Low crop yields due to continuous monocropping and deteriorating soil health in smallholder farmers' fields of sub-Saharan Africa have led to a quest for sustainable production practices with greater resource use efficiency. The aim of the study was to elucidate the short term effects of conservation agriculture (CA) systems on soil quality, crop productivity and profitability. In Balaka market and Ntonda sections of Manjawira Extension Planning Area (EPA), in Ntcheu district, central Malawi, we compared continuous monocropped maize (Zea mays) under conventional tillage practice (CP) with different CA systems in continuous monocropped maize (CAM) and intercropping with pigeonpea (Cajanus cajan) (CAMP), Mucuna pruriens (CAMM), and Lablab purpureus (L) (Sweet) (CAML). The study was conducted from 2008 to 2011 in 72 plots in 24 farmers' fields. In Balaka market section CA plots with maize + legumes produced up to 4.3 Mg ha(-1) of vegetative biomass against 3.5 Mg ha for maize alone in CP. In Ntonda section CA plots with maize + legumes produced up to 4.6 Mg ha(-1) of vegetative biomass against 2.4 Mg ha(-1) for maize alone in CP. In both sections, during the entire study period. CA did not have a negative effect on crop yields. During the drier seasons of 2009110 and 2010/11, CA had a positive effect on maize grain yield at both sites (average yield of 4.4 and 3.3 Mg ha(-1) in CA and CP respectively). However, associating maize with legumes reduced maize yields compared to CAM particularly in drier years of 2009-10 and 2010-11. Farmers spent at most 47 days ha(-1) producing maize under CA systems compared to 65 days ha(-1) spent under conventional tillage practices. However, total variable costs were higher in CA systems compared to conventional practice (at most US$416 versus US$344 ha(-1)). CAMP resulted in more than double gross margin compared to CPM (US$705 versus uS$344 hat). Infiltration estimated as time to pond was highest in CA maize legume intercrops (8.1 s) than CP (6.8 s). Although it was not feasible to directly estimate effects on water balances of these farmer-managed experiments, it can be assumed that the yield differences between CA and CP could be attributed to tillage and crop residue cover since other farm operations were generally the same. Intercropping maize and pigeonpea under CA presents a win-win scenario due to crop yield improvement and attractive economic returns provided future prices of maize and pigeonpea grain remain favourable. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • De Neve, S.
    • Sleutel, S.
    • Ngwira, A.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: Conservation agriculture (CA) characterised by minimal soil disturbance, permanent soil surface cover by dead or living plants and crop rotations is one way of achieving higher soil organic carbon (C) in agricultural fields. Sandy loam and loamy soil samples from zero tillage (ZT) and conventional tillage (CT) plots were taken from farmers' fields during the dry season in August 2006. Soil organic carbon (SOC) and soil organic nitrogen (SON), microbial biomass carbon (MB-C) and microbial biomass nitrogen (MB-N), C mineralization and SOC distribution in particle size fractions in 0-20 cm layer were evaluated. Forty eight farmers' fields were randomly sampled at four different locations in Central and Northern Malawi, representing ZT plots maintained for a different number of years, and ten fields under CT with similar soil type and crop grown were selected. SOC and SON in ZT fields were 44 and 41 % (4 years ZT) and 75 and 77 % (5 years ZT) higher, respectively, than CT plots. MB-C and MB-N in ZT fields were 16 and 44 % (4 years ZT) and 20 and 38 % (5 years ZT) higher, respectively, than CT plots. However, MB-C and MB-N in ZT fields were 27 and 25 % (2 years ZT) and 17 and 9 % (3 years ZT) lower than in CT plots. The proportion of the total organic C as microbial biomass C was relatively higher under CT than ZT treatments. The higher SOC and MB-C content in the ZT fields resulted in 10, 62, 57 % higher C mineralization rate in ZT plots of 3, 4 and 5 years of loamy sand soils and 35 % higher C mineralization rate in ZT plot of 2 years than CT of sandy loam soils in undisturbed soils in the laboratory. Simulating plough from the undisturbed soils that were used for C mineralization experiment resulted in linear curves indicating that all organic C was already depleted during the first incubation period. The relative distribution of soil organic matter (SOM) in silt and clay size fractions was strongly correlated (r = 0.907 and P a parts per thousand currency sign 0.01) with silt percentages. Easily degradable carbon pool (C-A,C-f) was correlated (r = 0.867 and P a parts per thousand currency sign 0.05) with organic carbon in sand size fraction. In developing viable conservation agriculture practices to optimize SOC content and long-term sustainability of maize production systems, priority should be given to the maintenance of C inputs, crop rotations and associations and also to reduced soil disturbance by tillage.
  • Authors:
    • Shah, S. C.
    • Chen, Z. S.
    • Adhikari, K. R.
    • Ghimire, R.
    • Dahal, K. R.
  • Source: Paddy and Water Environment
  • Volume: 10
  • Issue: 2
  • Year: 2012
  • Summary: Despite being a major domain of global food supply, rice-wheat cropping system is questioned for its contribution to carbon flux. Enhancing the organic carbon pool in this system is therefore necessary to reduce environmental degradation and maintain agricultural productivity. A field experiment (November 2002-March 2006) evaluated the effects of soil management practices such as tillage, crop residue, and timing of nitrogen (N) application on soil organic carbon (SOC) sequestration in the lowland of Chitwan Valley of Nepal. Rice ( Oryza sativa L.) and wheat ( Triticum aestivum L.) were grown in rotation adding 12 Mg ha -1 y -1 of field-dried residue. Mung-bean ( Vigna radiata L.) was grown as a cover crop between the wheat and the rice. Timing of N application based on leaf color chart method was compared with recommended method of N application. At the end of the experiment SOC sequestration was quantified for five depths within 50 cm of soil profile. The difference in SOC sequestration between methods of N application was not apparent. However, soils sequestered significantly higher amount of SOC in the whole profile (0-50 cm soil depth) with more pronounced effect seen at 0-15 cm soil depth under no-tillage as compared with the SOC under conventional tillage. Crop residues added to no-tillage soils outperformed other treatment interactions. It is concluded that a rice-wheat system would serve as a greater sink of organic carbon with residue application under no-tillage system than with or without residue application when compared to the conventional tillage system in this condition.
  • Authors:
    • Tiwari, S.
    • Tomar, N. S.
    • Tripathi, N.
    • Deshmukh, R.
  • Source: Physiology and Molecular Biology of Plants
  • Volume: 18
  • Issue: 1
  • Year: 2012
  • Summary: Drought tolerance is the essential trait that needs to be incorporated in cereal crops, particularly those grown under the rainfed cultivation. Drought tolerance being contributed by several regions of the genome requires identification of these regions, using suitable molecular markers. Therefore, present investigation was aimed at analyzing the genetic diversity present among the cultivars of rainfed and the irrigated areas with respect to the drought tolerant trait. In all, 14 RAPD and 90 ISSR markers were used to identify these genomic regions. Out of 14 RAPD markers, one RAPD primer exhibited polymorphic banding pattern with 18.6% polymorphism, clearly separating drought tolerant and drought susceptible genotypes. Out of 90 ISSR primers, only 3 ISSR primers revealed polymorphism in relation to the drought tolerance trait exhibiting 21.38% polymorphism.
  • Authors:
    • Portela, S. I.
    • Andriulo, A. E.
    • Restovich, S. B.
  • Source: Field Crops Research
  • Volume: 128
  • Year: 2012
  • Summary: The agricultural system of the Humid Pampas consists of continuous cropping of soybean and maize under no tillage. This system may loose nitrogen (N) through leaching during the early and final stages of summer crops and during fallow. In this study (2005-2011) we evaluated the effect of fall-winter species (rescue grass, ryegrass, oats, barley, vetch, rape seed and forage radish) and a mixture of vetch and oats used as cover crops on water and N dynamics and main crop yield. Above-ground biomass production and N uptake by cover crops ranged from 1.1 to 11.9 Mg ha(-1) and from 17 to 223 kg N ha(-1), respectively, depending on sowing and killing dates and on the preceding crop. At killing, soil nitrate content in treatments with cover crops was 50-90% lower than in the control, reducing spring N leaching risk. When preceding maize, cover crops were killed in winter or early spring and their low C/N ratio (12-38) favored N release through residue decomposition. Vetch and rape seed as predecessors of fertilized maize increased residual N by approximate to 50 kg NO3-N compared to the control, posing the risk of fall N leaching. When preceding soybean, cover crops were killed in spring and, although their C/N ratios were higher (13-85), crucifers and legumes increased soil nitrate content. Maize yield was related to soil N availability at sowing (control and legumes > crucifers > grasses) which was inversely related to the preceding cover crop C/N ratio at killing. In normal to high rainfall years there were no differences in soybean yield among treatments. Water use by cover crops did not affect the main crop production except during an exceptionally dry year. Best synchronicity between N release from cover crop residues and harvest crop demand was achieved with the oats-vetch mixture before maize and with grasses before soybean. (C) 2011 Elsevier B.V. All rights reserved.