• Authors:
    • Zhou, X. L.
    • Liao, M. L.
    • Feng, W. Q.
    • Qin, Y. S.
    • Tu,, S. H.
    • Sun, X. F.
  • Source: Southwest China Journal of Agricultural Sciences
  • Volume: 21
  • Issue: 1
  • Year: 2008
  • Summary: There were considerable differences in amounts of nutrient uptake by the rice cultivar Chuanxiangyou 9838 in different growing periods under no till rape-rice rotation in Sichuan. The rice cultivar absorbed the highest quantity of N in the elongation stage and followed by its maturity and tillering stages. Uptake of P kept a steady increase from seedling stage to its maturity, and the maximal uptake of K occurred during the elongation to earing stages. Based on the nutrient uptake characteristics of the rice cultivar Chuanxiangyou 9838, good nutrient management practices were therefore developed. Application of N should be conducted in early stages and no latter than its elongation. If the soil N supplying ability was not adequate after elongation, an extra N application should be considered to guarantee high yield and quality of the rice. Basal application of P was considered as a proper practice. When the soil as too sandy with low nutrient holding capacity, or too acidic or alkaline with strong ability to fix up P and lose bioavailability, it was better to split P fertilizer to meet requirement at its latter stages. K fertilizers could be applied in early to middle growing stages. If the soil was sandy, it should consider an extra K application after earing stage. It was found that the proper N application rate for the rice cultivar Chuanxiangyou 9838 under no till rape-rice rotation was approximately 165 kg/hm 2 N with a goal of 11 tonnes of rice yield.
  • Authors:
    • Correia, M. E. F.
    • Mercante, F. M.
    • Silva, R. F. da
    • Aquino, A. M. de
    • Guimaraes, M. de F.
    • Lavelle, P.
  • Source: European Journal of Soil Biology
  • Volume: 44
  • Issue: 2
  • Year: 2008
  • Summary: This work was aimed at evaluating the invertebrate macrofauna community in the soil, by means of its abundance and richness of groups under different plant covers in the no-till system. Evaluations were performed at the experimental field of Embrapa Agropecuaria Oeste, in the municipal district of Dourados-MS, on a Typic Hapludox under conventional, no-till, and natural systems. Samplings were performed in December 2000, June 2001, January 2002, and June 2002. Five soil monoliths measuring 0.25*0.25 m width and 0.30 m depth were sampled along a transect. Turnip residues before a corn crop (turnip/corn) and soybean residues before wheat and turnip crops (soybean/wheat and soybean/turnip) provided positive effects on the density and diversity of the edaphic macrofauna community.
  • Authors:
    • Radford, B. J.
    • Yule, D. F.
    • McGarry, D.
    • Playford, C.
  • Source: Soil & Tillage Research
  • Volume: 97
  • Issue: 2
  • Year: 2007
  • Summary: Heavy wheel traffic causes soil compaction, which adversely affects crop production and may persist for several years. We applied known compaction forces to entire plots annually for 5 years, and then determined the duration of the adverse effects on the properties of a Vertisol and the performance of maize and sorghum crops under no-till dryland cropping with residue retention. For up to 5 years after a final treatment with a 10 Mg axle load on wet soil, soil shear strength at 70-100 mm and cone index at 180-360 mm were significantly ( P<0.05) higher than in a control treatment, and soil water storage and grain yield were lower. We conclude that compaction effects persisted because (1) there were insufficient wet-dry cycles to swell and shrink the entire compacted layer, (2) soil loosening by tillage was absent and (3) there were fewer earthworms in the compacted soil. Compaction of dry soil with 6 Mg had little effect at any time, indicating that by using wheel traffic only when the soil is dry, problems can be avoided. Unfortunately such a restriction is not always possible because sowing, tillage and harvest operations often need to be done when the soil is wet. A more generally applicable solution, which also ensures timely operations, is the permanent separation of wheel zones and crop zones in the field-the practice known as controlled traffic farming. Where a compacted layer already exists, even on a clay soil, management options to hasten repair should be considered, e.g. tillage, deep ripping, sowing a ley pasture or sowing crop species more effective at repairing compacted soil.
  • Authors:
    • Yang, W.
    • Wu, Y.
    • Tu, X.
    • Tu, N.
    • Zhou, W.
    • Yi, Z.
  • Source: Research of Agricultural Modernization
  • Volume: 28
  • Issue: 4
  • Year: 2007
  • Summary: The effects of tillage and no-tillage, and different rates of straw mulching (without, half and full) on soil nutrient content and drought resistance of maize on dry land in Hunan Province (China) were determined. It was found that straw mulching promoted growth and development of maize in normal year (2004) but did not reduce the effect of high temperature and drought and prolonged filling stage 2-4 d in high temperature and drought year (2005). Cultivation measures slightly affected the growth and development of maize. No-tillage prolonged growth duration for around 2 days under high temperature and drought condition. Straw mulching increased plant height, leaf area, dry matter weight, 1000-grain weight and yield. The effects of full-straw mulching were better than those of half-straw mulching. Under the same mulch rates, the effect of tillage was better than no-tillage. The organic matter, readily available K and available P in soil were increased by straw mulching, which was more evident under no-tillage condition although soil organic matter content was slightly decreased without straw mulching. The soil water content was increased by straw mulching, and the effect of full-straw mulching was better than that of half-straw mulching. These results showed that straw mulching can alleviate the harmful effect of drought to a certain extent, and at the same time can increase soil nutrient content. Moreover, the combined effect of straw mulching and no-tillage on increasing soil nutrient content was more evident.
  • Authors:
    • Piza, R.
    • Camargo, R.
  • Source: Bioscience Journal
  • Volume: 23
  • Issue: 3
  • Year: 2007
  • Summary: The effect of different cover crops on maize yield was investigated in the second no-till year, in Passos, Minas Gerais, Brazil. White oats ( Avena sativa), black oats [ Avena nuda], Brachiaria decumbens [ Urochloa decumbens] and forage turnips were cultivated in the same plots as in the previous winter, and were subsequently sown with maize. The forage crops were sown in lines in May 2004 and desiccated in October 2004, after the determination of dry matter yield. Maize was sown in each plot and the soil organic matter and grain yield were determined at the end of the cropping season. The black oats yielded the greatest amount of mulch; however, this increase did not affect the soil organic matter, in relation to all other treatments, and maize yield in the no-till system.
  • Authors:
    • Simon, M.
    • Monaco, C.
    • Cordo, C.
  • Source: Australasian Plant Pathology
  • Volume: 36
  • Issue: 3
  • Year: 2007
  • Summary: Two Septoria Monitoring Nursery sets were tested for resistance in the field during three consecutive years. Different concentrations of oat grains covered with mycelia of Septoria tritici were applied as inoculum. The position of the disease on the plants and the severity of the Septoria leaf blotch infection were recorded at two growth stages. A comparison between leaf pulverisation and grain application as a source of conidia was made in the last year. The percentages of necrotic lesions and pycnidial coverage were recorded on the upper three leaves of the plants at the same growth stages as for previous years. With grain inoculation, the infection reached the 7th leaf of the plants with the maximum concentration applied at tillering stage. The best concentration to obtain the highest discrimination among resistances is 120 g/m 2. In the comparison of inoculation techniques, the results showed a higher necrosis and pycnidial coverage following leaf pulverisation than with the grain application treatment.
  • Authors:
    • Libardi, P. L.
    • Fernandes, F. C. S.
    • Silva, M. M. da
  • Source: Acta Scientiarum Agronomy
  • Volume: 29
  • Issue: Suplemento Espec
  • Year: 2007
  • Summary: The present study evaluated the effect of nitrogen levels and splittings on the chemical characteristics of a soil cropped with maize in succession to black oats at the establishment of the no tillage system. The experiment was carried out in a Red-Yellow Latosol (typic Hapludox), with 14% of clay in the 0-0.20 m soil layer. The work consisted of two maize crops (2003/04 and 2004/05) and a black oats one in between, as cover crop. The experimental design was randomized blocks in an incomplete factorial scheme, with four replications. Treatments consisted of nitrogen levels (60, 120 and 180 kg ha -1) and one control without nitrogen, besides the splittings (30 or 60 kg ha -1 at sowing, the balance in cover and 60 kg ha -1 at sowing, remaining top dressed). The following soil variables were evaluated: Ca, Mg, K, organic matter, P, H+Al, Al, sum of bases, CEC, pH and base saturation V(%). Ammonium sulfate fertilization top dressed promoted a pH decrease in all treatments after the second maize crop and the increase in the level of N decreased the contents of soil Ca, Mg and K.
  • Authors:
    • Carvalho, P. C. de F.
    • Cassol, L. C.
    • Anghinoni, I.
    • Flores, J. P. C.
    • Leite, J. G. dal B.
    • Fraga, T. I.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 31
  • Issue: 4
  • Year: 2007
  • Summary: The integration of farming and cattle production activities in no-tillage system areas with winter cover crops can be an income supplement for summer grain farmers. However, many of them are afraid of adopting this integration system because of possible negative effects of animal treading on soil attributes, mainly of those related to soil compaction. This study was conducted: (1) to determine the alterations in the soil physical attributes promoted by animal treading; and (2) to verify if the alterations in soil attributes due to animal treading affect soyabean establishment and grain yield. The experiment was carried out with a Rhodic Hapludox (Oxisol), under black oat [ Avena nuda] + ryegrass [ Lolium] pasture grazed at different heights (10, 20, 30 and 40 cm) and an ungrazed area. After one cycle of animal treading, there were no significant modifications in soil bulk density, porosity and compressibility at different grazing heights. However, soil density and compressibility were higher and the porosity lower in the grazed plots. The soyabean population and grain yield were not affected by modifications in the soil physical attributes.
  • Authors:
    • Souza, R. A.
    • Crispino, C. C.
    • Franchini, J. C.
    • Torres, E.
    • Hungria, M.
  • Source: Soil & Tillage Research
  • Volume: 92
  • Issue: 1/2
  • Year: 2007
  • Summary: The objective of this work was to identify soil parameters potentially useful to monitor soil quality under different soil management and crop rotation systems. Microbiological and chemical parameters were evaluated in a field experiment in the State of Parana, southern Brazil, in response to soil management [no-tillage (NT) and conventional tillage (CT)] and crop rotation [including grain (soybean, S; maize, M; wheat, W) and legume (lupin, L.) and non-legume (oat, O) covers] systems. Three crop rotation systems were evaluated: (1) (O/M/O/S/W/S/L/M/O/S), (2) (O/S/L/M/O/S/W/S/L/M), and (3) (O/S/W/S/L/M/O/M/W/M), and soil parameters were monitored after the fifth year. Before ploughing, CO 2-emission rates were similar in NT and CT soils, but plough increased it by an average of 57%. Carbon dioxide emission was 13% higher with lupin residues than with wheat straw; decomposition rates were rapid with both soil management systems. Amounts of microbial biomass carbon and nitrogen (MB-C and MB-N, respectively) were 80 and 104% higher in NT than in CT, respectively; however, in general these parameters were not affected by crop rotation. Efficiency of the microbial community was significantly higher in NT: metabolic quotient ( qCO 2) was 55% lower than in CT. Soluble C and N levels were 37 and 24% greater in NT than in CT, respectively, with no effects of crop rotation. Furthermore, ratios of soluble C and N contents to MB-C and MB-N were consistently lower in NT, indicating higher immobilization of C and N per unit of MB. The decrease in qCO 2 and the increase in MB-C under NT allowed enhancements in soil C stocks, such that in the 0-40 cm profile, a gain of 2500 kg of C ha -1 was observed in relation to CT. Carbon stocks also varied with crop rotation, with net changes at 0-40 cm of 726, 1167 and -394 kg C ha -1 year, in rotations 1, 2 and 3, respectively. Similar results were obtained for the N stocks, with 410 kg N ha -1 gained in NT, while crop rotations 1, 2 and 3 accumulated 71, 137 and 37 kg of N ha -1 year -1, respectively. On average, microbial biomass corresponded to 2.4 and 1.7% of the total soil C, and 5.2 and 3.2% of the N in NT and CT systems, respectively. Soil management was the main factor affecting soil C and N levels, but enhancement also resulted from the ratios of legumes and non-legumes in the rotations. The results emphasize the importance of microorganisms as reservoirs of C and N in tropical soils. Furthermore, the parameters associated with microbiological activity were more responsive to soil management and crop rotation effects than were total stocks of C and N, demonstrating their usefulness as indicators of soil quality in the tropics.
  • Authors:
    • Pereira, J.
    • Prior, M.
    • Uribe-Opazo, M.
    • Nobrega, L.
    • Lopes, R.
  • Source: Acta Scientiarum Agronomy
  • Volume: 29
  • Issue: Suplemento Espec
  • Year: 2007
  • Summary: This study evaluated alterations in the physical properties water content, soil density and porosity in areas under no tillage and tillage systems in the cultures of soybean and maize in three agricultural years. The experiment was carried out at the Experimental Nucleus of Agricultural Engineering of Unioeste (Cascavel, state of Parana). Soybean culture occurred in the first two years and in the third year maize, as summer crop, black oats and forage turnip as winter cover crops. During these three years the study observed reduction of water content and soil density and increase of porosity. The variations as regards the physical properties of the soil showed direct proportional relation between water content and soil density and was in inverse proportion for soil porosity. The soil presented improvements on its physical conditions for the porosity increase and density reduction with the black oats and forage turnip crops and maize. The soybean/maize management in rotation with black oats and forage turnip showed more adequate in the improvement of the physical conditions of the soil as compared with the management systems, since neither of the systems had a major impact in the improvements of the physical properties evaluated throughout this whole period.