• 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:
    • 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:
    • Prasuhn, V.
  • Source: Soil & Tillage Research
  • Volume: 120
  • Year: 2012
  • Summary: The positive effects of soil conserving farming methods have mostly been demonstrated using small test plots. The present study is aimed at confirming that they also occur on the catchment scale. The impact of crops and soil tillage practises on the extent of soil erosion was determined in 203 crop fields over 10 years in the Swiss Midlands. Soil erosion totalled 1969 t or 0.75 t ha(-1) yr(-1). Most erosion took place in winter wheat fields (33%), which accounted for 22% of the crop area. Second and third most erosion was observed in potato (26%) and fallow (14%) fields. By far the highest mean soil loss was found for potatoes, at 2.87 t ha(-1) yr(-1). Fallow (1.06 t ha(-1) yr(-1)) and winter wheat (1.05 t ha(-1) yr(-1)) fields were also relatively susceptible to soil erosion. In contrast, values for soil loss below mean were observed for maize (0.44 t ha(-1) yr(-1)), sugar beet (0.27 t ha(-1) yr(-1)), and rape seed (0.39 t ha(-1) yr(-1)). 88% of soil erosion took place on plough tilled land (PT), 9% on non-ploughed land with less than 30% surface residue cover (RT), 1% on mulch-tilled land with more than 30% surface residue cover (MT), and 2% in non-tilled or strip-tilled land with >30% soil cover (NT). At 0.07 and 0.12 t ha(-1) yr(-1), respectively, the mean soil loss in MT and NT fields was more than an order of magnitude lower than that under PT (1.24 t ha(-1) yr(-1)). Field mappings confirmed the positive effects of the soil conserving soil tillage practises. The risk of soil erosion was significantly influenced by crop rotation. The carry-over effects should be taken into account when studying the effects of cropping methods on soil erosion. (C) 2012 Elsevier B.V. All rights reserved.
  • 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:
    • Oliveira, E. B. de
    • Moraes, A. de
    • Pelissari, A.
    • Reis, E. F. dos
    • Ruaro, L.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 47
  • Issue: 4
  • Year: 2012
  • Summary: The objective of this work was to assess the effect of soil management systems and winter cover crops on the number of propagules of Fusarium spp. in soil, the incidence of sudden death syndrome (SDS), and the productivity of the soybean cultivars CD 206 and FT Fenix. Two experiments were carried out in the 2006/2007 and 2007/2008 crop years. The experimental design was a randomized complete block in a split-split plot arrangement, with three replicates. Two soil tillage systems were evaluated: no-tillage and plowed soil at a depth of 25 cm. The soil covers used were: black oat, with two planting densities; black oat+vetch; ryegrass; and fallow. The incidence of the disease in the 2006/2007 crop year in the cultivar FT Fenix was lower than in CD 206. In the 2007/2008 crop, there was no significant difference. There was an increase in productivity, of 125 kg ha -1, in the plowed treatment, when compared to no-tillage. The cover with black oat+vetch showed a higher number of propagules of Fusarium spp. in soil in the 2006/2007 crop year. However, in the second year, this difference was not observed. The soil management systems and winter cover crops used do not influence the incidence of SDS in soybean cultivars or the number of Fusarium spp. propagules in soil. The plowed system provides an increase in soybean yield in the second year of management.
  • 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.
  • Authors:
    • Marins, A. C. de
    • Souza, S. N. M. de
    • Santos, R. F.
    • Veloso, G.
    • Secco, D.
    • Rosa, H. A.
    • Borsoi, A.
  • Source: Food, Agriculture and Environment (JFAE)
  • Volume: 10
  • Issue: 2 part 3
  • Year: 2012
  • Summary: Certain soil physical characteristics such as resistance to penetration (Rs) and bulk density (Ds) are extremely important, and are also indicators of the soil structural quality. This paper aims at evaluating the use of four cover crop species in the reduction of density and soil resistance to penetration in areas where a no-till farming system is applied. The so-called "regenerator" species, which act in soil structure, were considered treatments, and consisted of four species: showy rattlebox ( Crotalaria spectabilis), moha grass ( Setaria italica), pigeon pea ( Cajanus cajan), sorghum ( Sorghum bicolor), and yet the control (an area without crops). Soil bulk density evaluations were carried out according to the methodology recommended by EMBRAPA, in the following depths: 0.0-0.1, 0.1-0.2 and 0.2-0.3 m. Sampling was carried out with five replications for the crop row and five for the spacing between each crop row, in each experimental unit (5 m * 5 m), up to 0.40 m in depth. An experimental design was 5*4*2 factorial, meaning 5 treatments, 4 depths and 2 sampling conditions. The species studied, especially the pigeon pea and the sorghum, showed a great potential to improve soil structural state, for they showed figures to Ds and Rs that were lower than the ones from the area without crops.
  • Authors:
    • Feng, G.
    • Wendling, L.
    • Sharratt, B.
  • Source: Aeolian Research
  • Volume: 5
  • Year: 2012
  • Summary: Winter wheat - summer fallow is the crop rotation used on more than 1.5 million ha in the Pacific Northwest United States. Land maintained using conventional summer fallow is susceptible to wind erosion because multiple tillage operations during the fallow period expose the soil to high winds. Alternative management strategies are needed that protect the soil surface from erosion during summer fallow. Surface characteristics were examined after subjecting the loessial soil to seven (conventional), five (reduced), three (minimum), and zero (no) tillage operations during the fallow period. Surface residue biomass and roughness and soil crust, aggregation, strength, and water content were measured after tillage and sowing operations. No tillage resulted in a more persistent and thicker soil crust and greater residue cover, silhouette area index (SAI), and penetration resistance than conventional and reduced tillage. For those treatments subject to tillage, minimum tillage resulted in a thicker soil crust and greater residue cover, SAI, ridge roughness, mean aggregate diameter, and penetration resistance as compared to conventional or reduced tillage after primary tillage. Near the end of the fallow period, minimum tillage resulted in 15% greater residue cover than conventional tillage. Soil loss from minimum tillage is expected to be 50% of conventional tillage based upon these differences in residue cover. This study suggests that minimum tillage is an alternative strategy to conventional tillage for reducing wind erosion in the wheat-fallow region of the Pacific Northwest. Published by Elsevier B.V.
  • Authors:
    • Sakar, D.
    • Hashem, A.
    • Jeuffroy, M. H.
    • Turner, N. C.
    • Johansen, C.
    • Siddique, K. H. M.
    • Gan, Y.
    • Alghamdi, S. S.
  • Source: Agronomy for Sustainable Development
  • Volume: 32
  • Issue: 1
  • Year: 2012
  • Summary: Although there is increasing awareness of the importance of food legumes in human, animal and soil health, adoption of improved production technologies for food legume crops is not proceeding at the same pace as for cereal crops. Over the previous decade, the only food legumes to have shown significant production increases have been chickpea, lentil and faba bean in North America, chickpea in Australia, and faba bean in Europe. In smallholder farming in developing countries, production trends have mostly been static or have declined over the past decade despite the existence of technology that should permit higher and more stable yields. Ability to reverse negative trends is jeopardized by climate change as food legumes are mostly grown rainfed and are being exposed to increasingly variable and extreme weather. This review examines recent innovations in cultivation technology for the major food legumes-chickpea, lentil, dry pea, faba bean, lupin, common bean, mung bean, black gram, cowpea, and pigeonpea-and explores constraints to their adoption, particularly by resource-poor smallholder farmers. Conservation agriculture, involving minimum soil disturbance, maximum soil cover, and diverse rotations, has contributed to sustainable cropping system production in large-scale commercial farming systems in the Americas, Europe, Australia, and Turkey. Temperate food legumes have been incorporated into such systems. Adoption of conservation agriculture is only just beginning for smallholder farming in Asia and Africa, catalyzed by the development of low-cost implements suitable for minimum tillage. Water use efficiency improves with conservation agriculture as it allows for earlier planting, reduced soil evaporation, better weed management, and increased access to nutrients. Ecosystem-based approaches to plant nutrition are evolving which place more reliance on accessing organic and mineral reservoirs than in replenishing the immediately available pool with chemical fertilizers, leading to enhanced nutrient use efficiency of cropping systems. Ecosystem-based approaches are also being applied to management of weeds, diseases, and insect pests of food legumes, again with decreased reliance on synthetic chemicals. In achieving sustainable agricultural production systems, there is increasing realization of the need to move towards the tenets of organic agriculture, as exemplified in conservation agriculture and ecosystem-based approaches to plant nutrition and pest management. This does not necessarily imply a desire to qualify for organic product certification but more a realization of the need for sustainable agriculture. The movement towards conservation and organic agriculture encourages greater inclusion of food legumes, and legumes generally, in cropping systems. Unfortunately, however, technology transfer to resource-poor farming situations, where most food legumes are produced, remains a major bottleneck to meeting global demand. More participatory approaches to technology development, testing, and dissemination are required than hitherto practiced. It is suggested that this process could be enhanced by better focusing on major constraints within the value addition chain for food legumes.
  • Authors:
    • Pereira Nóbrega, L. H.
    • dos Santos, D.
    • Gonçalves Junior, A. C.
    • de Souza, E. G.
    • Tavares-Silva, C. A.
  • Source: Food, Agriculture and Environment (JFAE)
  • Volume: 10
  • Issue: 1
  • Year: 2012
  • Summary: No-tillage system is an alternative agricultural management to protect soil; however, the cover crops association is required in crop rotation or succession, allowing an amount of nutrients supply and organic matter to soil through mineralization of plant residues. Thus, this trial aimed at evaluating the effects of crops succession on soybean yield and on chemical properties of soil: calcium, magnesium and aluminium saturation (m%). The trial was carried out in Cafelandia (PR) city, in a typical eutrophic red latosol, from June 2008 to March 2010. The experimental design was completely randomized with five treatments: black oat; consortium 1 (turnip and black oat); consortium 2 (turnip, black oat and common vetch), wheat and fallow, with six replications in a 2 ha area, in four periods during two agricultural harvests, in order to record chemical analyses of soil in a depth from 0 to 0.2 m. The cover crops management was with roll-knife, while wheat was harvested with an automotive combine. Soybean was sown in summer and its yield was determined for each treatment. Winter cover crops influenced on Mg concentration in soil when evaluated after soybean harvest in 2010, so that, black oat and the second consortium were the main responsible for such increase, although, the treatments showed no effect on soybean yield during the 2009/2010 harvest.