• Authors:
    • Silveira, F. de M.
    • Silva, E. D. B. da
    • Pauletti, V.
    • Favaretto, N.
    • Vezzani, F. M.
    • Dieckow, J.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 35
  • Issue: 5
  • Year: 2011
  • Summary: The use of manure in agricultural system is a possibility to dispose of the waste generated in animal production, but improper use can cause environmental problems. The general objective of this study was to evaluate carbon and nitrogen concentrations and losses in runoff in four doses of liquid dairy manure (0, 60, 120, 180 m 3 ha -1 yr -1) applied to a silt clay loam Oxisol with 13% slope, in no-till with soybean, oat, corn, and wheat in crop rotation. The runoff was collected for two years and seven months in 60 L containers after every rain with runoff from at least one plot. Soluble nutrients were analyzed in runoff samples filtered through a 0.45 m membrane and total nutrients in unfiltered samples. The application of liquid dairy manure reduced the losses of organic carbon and nitrogen, with positive consequences for water quality. However, higher rates tended to increase the concentrations of these elements and, consequently, reduce water quality. The weighted average concentrations of nitrate were below the limit allowed by Brazilian legislation, but ammonium exceeded the threshold values, indicating the need of control measures to prevent the runoff from reaching the water bodies, even in no-tillage systems. It should be pointed out that these data were obtained under low potential polluting conditions, i.e, on 13% slope, low rainfall and with a minimum interval of ten days between manure application and rainfall. Further studies should also evaluate nitrate leaching.
  • Authors:
    • Chenglin, M.
    • Chunsheng, L.
    • Honglei, J.
    • Lichun, W.
    • Hongjie, T.
  • Source: Soil & Tillage Research
  • Volume: 107
  • Issue: 1
  • Year: 2010
  • Summary: The stalk-stubble breaking and mulching process is a core technique for some conservation tillage system. Over the past 10 years, this technique has been widely adopted in the dry farming area of northern China. On the basis of analyzing the existing problems in stalk-breaking and stubble-breaking machines, we have developed a combined stalk-stubble breaking and mulching machine with two frames fixed together, the stalk and stubble-breaking blade rotors were mounted respectively on the frames. The machine can be used to break the maize ( Zea mays L.) stalk and stubble and bury about one-third of the broken stalk and stubble in the soil, preventing them being blown away by wind. This paper describes the structural features of the machine, the design of main working parts, determination of the parameters of the central position of the two blade rotors, and presents the performance test results. The tests showed that the machine had a stalk-breaking rate of 89% and the vegetation coverage rate reached 67.9%, which meets the agro-technical requirements in the dry farming area of northern China.
  • Authors:
    • Brown, S.
    • Pearson, T.
  • Year: 2010
  • Summary: From exec. summary: ...The purpose of the study was to develop a methodology that could be used to calculate emission reduction offsets from activities associated with nitrogen-based fertilizers in US agriculture. To have credibility in the developing carbon market the methodology would have to accurately represent the impact on the atmosphere and would involve the input of significant site-specific data. Thus the Intergovernmental Panel on Climate Change (IPCC)'s Tier 1 approach is far from sufficient as it simply multiplies the quantity applied by defaults to calculate emissions. Yet a methodology must not be excessively expensive to implement as it would preclude the possibility of any project being implemented thus direct measurement of nitrous oxide from fields using measurement chambers could not be considered. A methodology was chosen for testing that included site specific information on type of fertilizer, soil carbon concentration, drainage, pH, soil texture and crop type. The highly parameterized, tested and peer-reviewed model DNDC (Denitrification-Decomposition) was used to estimate the "real" atmospheric impact at the test sites. Test sites were chosen in Arkansas (cotton), Iowa (corn) and California (lettuce) for the 2009 growing season.... Neither the IPCC Tier 1 method nor the new method proposed here based on Bouwman et al (2002) are sufficient for an offset project methodology that would be able to evaluate atmospheric impact of a broad range on fertilizer management practices. Therefore alternative approaches must be considered.... This comparison highlighted a further weakness of the simplified models; the simplified models can only evaluate the impacts of changes in quantify of fertilizer applied not in the methods of application....The recommendation arising from this report is to develop an offset methodology based on the application of DNDC for projects. A DNDC methodology will require expertise but atmospheric integrity is better guaranteed, monitoring would likely be inexpensive and costs would be low considering that offset projects are likely to consist of aggregations of large numbers of farms.
  • Authors:
    • Sousa, D. M. G. de
    • Rein, T. A.
  • Source: Informações Agronômicas
  • Issue: 126
  • Year: 2009
  • Summary: Soyabean monoculture with inadequate agricultural practices has resulted in losses of soil organic matter in the Brazilian cerrado, especially in sandy soils. This has led to erosion, reduced cation exchange capacity and water storage, and diminished fertilizer use efficiency. One of the ways of avoiding the loss of soil organic matter is to reduce tillage, as in the system of direct (as opposed to conventional) planting, and the use of this system is growing in the cerrado region. This paper reviews work that has been done on the correction of soil acidity and fertilizing with macronutrients in the direct planting system, both before and after crop establishment. The section on soil acidity discusses both surface (0-20 cm) and subsurface (20-60 cm) acidity, and the effects of correction with limestone or gypsum under conventional and no tillage systems, and on cotton and soyabean yields under a direct planting system. The section on fertilizers looks at the effects of liming, conventional and no tillage systems and dry farming on soil macronutrient content (with particular reference to nitrogen, phosphorus and potassium) and crop yield (with data for maize). Soil organic matter content is also compared under conventional and no tillage systems.
  • Authors:
    • Gomes, A. da S.
    • Vernetti Junior, F. de J.
    • Schuch, L. O. B.
  • Source: Revista Brasileira de Agrociencia
  • Volume: 15
  • Issue: 1/4
  • Year: 2009
  • Summary: In the state of Rio Grande do Sul, Brazil, there are 5,5 million ha of tilled plain soils that have been partly cropped with irrigated rice ( Oryza sativa L.), the remainder area lodging extensive beef cattle raising. This research was undertaken aiming chiefly to identify one or more technical solutions to the agribusiness associated with the agro-ecosystem of the "Temperate Climate region". The work was carried out at experimental area of Lowland Agricultural Research Station of Embrapa Temperate Climate (31degrees 52′S; 52degrees 21′24W), Brazil. The experiment was planned in a split-plot randomized blocks design with three replications and performed along ten years. The treatments were successive winter and spring-summer crops growing during five years, followed by two years of no-cropping and then three years of irrigated rice crop growing. The spring-summer crops were corn and soybean, besides rice; the winter crops were poaceae (Ps), fabaceae (Fs), species mixtures (Ms), turnip (T) and native grass species (NG). Seeding was performed either by no-ploughing (PD) or conventional (SC). Grain and dry-matter yields were estimated and evaluated. The evaluations were performed by analysis of variance (F and Duncan tests). The results allowed the following conclusions: (1) Ps and Fs had the highest yields; (2) corn yields were higher when its crop followed Fs species and/or Ms; (3) corn crop in tiled plains shows better performance when planted in no-plow; (4) soybean crop following Ps performed better than following Fs; (5) no-plough favors the soybean crop in tilled plains; (6) irrigated rice yields are higher succeeding the corn crop.