• Authors:
    • Dubois, D.
    • Gaillard, G.
    • Schaller, B.
    • Chervet, A.
    • Nemecek, T.
    • Huguenin-Elie, O.
  • Source: Agricultural Systems
  • Volume: 104
  • Issue: 3
  • Year: 2011
  • Summary: Extensive or low-input farming is considered a way of remedying many problems associated with intensive farming practices. But do extensive farming systems really result in a clear reduction in environmental impacts, especially if their lower productivity is taken into account? This question is studied for Swiss arable cropping and forage production systems in a comprehensive life cycle assessment (LCA) study. Three long-term experiments (DOC) experiment comparing bio-dynamic, bio-organic and conventional farming, the "Burgrain" experiment including integrated intensive, integrated extensive and organic systems and the "Oberacker" experiment with conventional ploughing and no-till soil cultivation, are considered in the LCA study. Furthermore, model systems for arable crops and forage production for feeding livestock are investigated by using the Swiss Agricultural Life Cycle Assessment method (SALCA). The analysis covers an overall extensification of cropping systems and forage production on the one hand and a partial extensification of fertiliser use, plant protection and soil cultivation on the other. The overall extensification of an intensively managed system reduced environmental impacts in general, both per area unit and per product unit. In arable cropping systems medium production intensity gave the best results for the environment, and the intensity should not fall below the environmental optimum in order to avoid a deterioration of eco-efficiency. In grassland systems, on the contrary, a combination of both intensively and extensively managed plots was preferable to medium intensity practices on the whole area. The differences in yield, production intensity and environmental impact were much more pronounced in grassland than in arable cropping systems. Partial extensification of a farming system should be conceived in the context of the whole system in order to be successful. For example, the extensification solely of fertiliser use and soil cultivation resulted in a general improvement in the environmental performance of the farming system, whereas a reduction in plant protection intensity by banning certain pesticide categories reduced negative impacts on ecotoxicity and biodiversity only, while increasing other burdens such as global warming, ozone formation, eutrophication and acidification per product unit. The replacement of mineral fertilisers by farmyard manure as a special form of extensification reduced resource use and improved soil quality, while slightly increasing nutrient losses. These results show that a considerable environmental improvement potential exists in Swiss farming systems and that a detailed eco-efficiency analysis could help to target a further reduction in their environmental impacts.
  • Authors:
    • Benjamin, J. G.
    • Nielsen, D. C.
    • Vigil, M. F.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 2
  • Year: 2011
  • Summary: No-till dryland winter wheat ( Triticum aestivum L.)-fallow systems in the central Great Plains have more water available for crop production than the traditional conventionally tilled winter wheat-fallow systems because of greater precipitation storage efficiency. That additional water is used most efficiently when a crop is present to transpire the water, and crop yields respond positively to increases in available soil water. The objective of this study was to evaluate yield, water use efficiency (WUE), precipitation use efficiency (PUE), and net returns of cropping systems where crop choice was based on established crop responses to water use while incorporating a grass/broadleaf rotation. Available soil water at planting was measured at several decision points each year and combined with three levels of expected growing season precipitation (70, 100, 130% of average) to provide input data for water use/yield production functions for seven grain crops and three forage crops. The predicted yields from those production functions were compared against established yield thresholds for each crop, and crops were retained for further consideration if the threshold yield was exceeded. Crop choice was then narrowed by following a rule which rotated summer crops (crops planted in the spring with most of their growth occurring during summer months) with winter crops (crops planted in the fall with most of their growth occurring during the next spring) and also rotating grasses with broadleaf crops. Yields, WUE, PUE, value-basis precipitation use efficiency ($PUE), gross receipts, and net returns from the four opportunity cropping (OC) selection schemes were compared with the same quantities from four set rotations [wheat-fallow (conventional till), (WF (CT)); wheat-fallow (no-till), (WF (NT)); wheat-corn ( Zea mays L.)-fallow (no-till), (WCF); wheat-millet ( Panicum miliaceum L.) (no-till), (WM)]. Water use efficiency was greater for three of the OC selection schemes than for any of the four set rotations. Precipitation was used more efficiently using two of the OC selection schemes than using any of the four set rotations. Of the four OC cropping decision methods, net returns were greatest for the method that assumed average growing season precipitation and allowed selection from all possible crop choices. The net returns from this system were not different from net returns from WF (CT) and WF (NT). Cropping frequency can be effectively increased in dryland cropping systems by use of crop selection rules based on water use/yield production functions, measured available soil water, and expected precipitation.
  • Authors:
    • Mendes, I.
    • de Castro Lopes, A.
    • Nunes, R.
    • Gomes de Sousa, D.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 35
  • Issue: 4
  • Year: 2011
  • Summary: MANAGEMENT SYSTEMS AND THE CARBON AND NITROGEN STOCKS OF CERRADO OXISOL UNDER SOYBEAN-MAIZE SUCCESSION Carbon and N stocks in soils are determined by the balance between addition and losses, and tillage and cropping systems are decisive in this process. This study aimed to evaluate the effect of soil management systems based on tillage, cover crops and P fertilization on C and N stocks in physical fractions of the soil organic matter and on microbial biomass and respiration in a soil after 11 years under soybean-maize rotation. The experiment was initiated in 1999 in an Oxisol with adequate level of available P to obtain form 80 to 90 % of potential yields of annual crops. The experiment was arranged in a split-plot design in randomized blocks, with three management systems based on soil tillage and cover crop (conventional tillage with pearl millet, no-tillage with pearl millet and no-tillage with velvet bean) assigned to the main plots and two P levels (0 and 100 kg ha(-1) yr(-1) of P2O5 as triple superphosphate applied at sowing) in subplots. Soil samples were collected at the grain filling stage of soybean (March 2010), from the soil layers 0-5, 5-10 and 10-20 cm, and subjected to physical fractionation of organic matter and microbial analysis. The no-tillage system resulted in stratification of organic C and N while conventional tillage resulted in a more homogeneous distribution in the 0-20 cm layer. Phosphorus fertilization for 11 years led to an accumulation of organic C and N in the soil, regardless of tillage and cover crop systems. Higher stocks of organic C and total N, higher microbial biomass C and lower microbial respiration were found under no-tillage than conventional tillage, both with pearl millet as cover crop. In the no-tillage systems, greater stocks of organic C and total N, similar microbial biomass C and higher microbial respiration were found with pearl millet as cover crop compared to velvet bean. The conversion rate of C added by crops to soil organic C was 4.0, 8.2 and 14.3 % for conventional tillage with pearl millet and no-tillage with pearl millet and with velvet bean, respectively.
  • Authors:
    • Smith, D. R.
    • Gal, A.
    • Vyn, T. J.
    • Omonode, R. A.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 1
  • Year: 2011
  • Summary: Few experiments have directly compared the long-term effects of moldboard, chisel, and no-till tillage practices on N 2O emissions from the predominant crop rotation systems in the midwestern United States. This study was conducted from 2004 to 2006 on a tillage and rotation experiment initiated in 1975 on a Chalmers silty clay loam (a Typic Endoaquoll) in west-central Indiana. Our objectives were to assess (i) long-term tillage (chisel [CP], moldboard plow [MP], and no-till [NT]), rotation (continuous corn [ Zea mays L.] and corn-soybean [ Glycine max (L.) Merr.]), and rotation * tillage interaction effects on soil N 2O emission, and (ii) how soil N 2O emission is related to environmental factors during corn production under identical N fertilizer management. Seasonal N 2O emissions were measured at intervals ranging from a few days to biweekly for up to 14 sampling dates in each growing season for corn. Nitrous oxide emissions during the growing season were significantly affected by tillage and rotation but not their interaction; however, 50% of total emissions occurred shortly after N application regardless of tillage or rotation practices. Seasonal cumulative emissions were significantly lower under NT but not statistically different for CP and MP. Overall, emissions under NT were about 40% lower relative to MP and 57% lower relative to CP. Rotation corn lowered N 2O emissions by 20% relative to continuous corn. Higher N 2O emission under MP and CP appeared to be driven by soil organic C decomposition associated with higher levels of soil-residue mixing and higher soil temperatures.
  • Authors:
    • Ortega, A. L.
  • Source: Archives of Agronomy and Soil Science
  • Volume: 57
  • Issue: 6
  • Year: 2011
  • Summary: The permanent bed planting system for wheat ( Triticum aestivum L.) production has recently received additional attention. Studies using hard red spring wheat (cultivar Nahuatl F2000) were conducted at two locations in central Mexico. The studies included the installation of three furrow diking treatments, two granular N timing treatments and three foliar N rates applied at the end of anthesis. The objective was to evaluate the effect of these factors on wheat grain yield, yield components and grain N in a wheat-maize ( Zea maize L.) rotation with residues of both crops left as stubble. Results indicated that diking in alternate furrows increased both grain yield and the final number of spikes per m 2. The split application of N fertilizer enhanced the number of spikes per m 2 and grain N uptake, but the effect on grain yield was inconsistent. Similarly, grain protein increased with the foliar application of 6 kg N ha -1, depending upon the maximum temperature within the 10 days following anthesis. The normalized difference vegetative index (NDVI) readings collected at four growth stages were generally higher for the split N application than for the basal N application at planting. Grain N uptake was associated to NDVI readings collected after anthesis.
  • Authors:
    • Forgey, D.
    • Beck, D.
    • Osborne, S. L.
    • Dagel, K. J.
  • Source: Agricultural Journal
  • Volume: 6
  • Issue: 2
  • Year: 2011
  • Summary: Incorporating cover crops into current production systems can have many beneficial impacts on the current cropping system including decreasing erosion, improving water infiltration, increasing soil organic matter and biological activity but in water limited areas caution should be utilized. A field study was established in the fall of 2007 to evaluate the impact of incorporating cover crops into a no-till crop production system in Central South Dakota. Cover crops utilized in the experiment were: cowpea ( Vigna sinensis), lentils ( Lens culinaris), canola ( Brassica napus), cow/can/len, cow/can, can/len, radish ( Raphanus sativus)/cow/can/len and turnip ( Brassica napa)/cow/len/can combos all compared to no-cover crop. Cover crops were allowed to grow throughout the fall and winter killed. Cover crop biomass was collect prior to a killing frost. The following spring corn was planted and in-season growth and grain yield was evaluated. When cover crops were incorporated into the production practices there was a significant increase in grain yield compared to the no cover crop treatment without additional nitrogen. While when nitrogen was applied to the corn crop yields did not increase as dramatically compared to the no cover crop treatment. Fall cover crops had the ability to scavenge residual soil nitrate and make it plant available for the following crop providing a positive environmental benefit beyond the above mentioned benefits.
  • 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:
    • Parr, M.
    • Grossman, J. M.
    • Reberg-Horton, S. C.
    • Brinton, C.
    • Crozier, C.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 6
  • Year: 2011
  • Summary: Sixteen winter annual cover crop cultivars were grown in North Carolina to determine total N accumulation, biological N fixation (BNF) potential, and compatibility with a roller-crimper-terminated organic corn ( Zea mays L.) production system. Cover crops and termination dates were tested in a stripped block design. Treatments included hairy vetch ( Vicia villosa Roth), common vetch ( Vicia sativa L.), crimson clover ( Trifolium incarnatum L.), Austrian winter pea ( Pisum sativum L.), berseem clover ( Trifolium alexandrinum L.), subterranean clover ( Trifolium subterraneum L.), narrow leaf lupin ( Lupinus angustifolius L.), and Balansa clover ( Trifolium michelianum Savi.), as well as bicultures of rye ( Secale cereale L.), hairy vetch, and Austrian winter pea. Roller-crimper termination occurred in mid-April, early May, and mid-May. Total biomass, N concentration, and C/N ratios were determined for cover crops at all roll times and natural 15N abundance at the optimal kill date. Hairy vetch and crimson clover monocultures had the greatest overall biomass in 2009, and bicultures the greatest biomass in 2010. Crimson clover successfully terminated in late April, hairy vetch and Austrian winter pea in mid-May, and berseem clover and common vetch in late May. All cover crops except lupin and subterranean clover derived between 70 and 100% of their N from the atmosphere. Corn response to cover crop mulches was significantly affected by the time of rolling, with poor stands resulting from competition with insufficiently terminated mulches. Crimson, Balansa, and subterranean clover mulches resulted in poor corn yields despite relatively high levels of total N. The highest corn yields were achieved in hairy vetch and rye plus hairy vetch bicultures.
  • Authors:
    • Pinto, C.
    • Sizenando Filho, F.
    • Cysne, J.
    • Pitombeira, J.
  • Source: Revista Verde de Agroecologia e Desenvolvimento Sustentavel
  • Volume: 6
  • Issue: 2
  • Year: 2011
  • Summary: Field experiments were conducted in Ceara, Brazil, to study the response of castor bean intercropping with sesame, cotton, maize and cowpea under dryland conditions. The intercropping indices evaluated were LER, LEC, ATER, mean of LER and ATER, SPI, CoR, RCC, CR, A and ALY. Castor beans and intercrops had reductions in yield. Based on the LER, LEC, CRA, AYL and CoR in the intercropping systems, the castor bean + maize treatment was the most advantageous under dryland farming. Based on the A and ALY indices, castor bean was dominated by sesame, cotton, maize and cowpea. The castor bean, cotton, sesame and castor bean, castor bean, maize treatments showed yield stability, which was characterized by the productivity index of the system (SPI).
  • 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.