• Authors:
    • Figueiredo, G. C.
    • Medeiros, J. C.
    • Giarola, N. F. B.
    • Fracetto, F. J. C.
    • Silva, A. P. da
    • Cerri, C. E. P.
  • Source: Plant Soil
  • Volume: 338
  • Issue: 1-2
  • Year: 2011
  • Summary: The decomposition rate of soil organic matter (SOM) is affected by soil management practices and particularly by the physical and hydraulic attributes of the soil. Previous studies have indicated that the SOM decomposition is influenced by the Least Limiting Water Range (LLWR). Therefore, the objective of this study was to relate the C-CO 2 emissions to the LLWR of the surficial layer of soil under two management systems: no-tillage (NT), conducted for 20 years, and conventional tillage (CT). Soil in NT presented greater soil organic carbon (SOC) stocks than in CT. Emissions of C-CO 2 were greater in the NT than in the CT, because of the greater carbon stocks in the soil surface layer and the greater biological activity (due to the improvement of the soil structure) in NT as compared to CT. The use of LLWR associated with the measurement of C-CO 2 emissions from the soil could help to predict the efficacy of the adopted management system for trapping carbon in the soil.
  • 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:
    • de Assis, R. L.
    • Madari, B. E.
    • Petter, F. A.
    • Pacheco, L. P.
    • Leandro, W. M.
    • Barbosa, J. M.
    • Oliveira de Almeida Machado, P. L.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 5
  • Year: 2011
  • Summary: The cover crops in no-till system can contribute to the formation of mulch and nutrient cycling to annual crops in succession. The objective of this study was to evaluate biomass production and nutrient cycling of cover crops sown in the second growing season, in crop rotation after upland rice and soybean, in no-tillage and conventional tillage systems, on a Red Latassol of Rio Verde, state of Goias, from April 2008 to April 2010. The experiment was evaluated in randomized strips, in a 5 x 6 factorial design, with four replications. In the horizontal strips two soil management systems (after three years of no-tillage and conventional systems) were evaluated and the cover crops in the vertical strips. Biomass and ground cover and nutrient cycling rates were only evaluated in the no-till treatments, in a 5 x 6 factorial arrangement, where the plots were subdivided, corresponding to six harvest dates of dried biomass 0, 15, 30, 60, 90 and 120 days after cutting of the cover crops. The following cover crops were sown in the second growing season: Brachiaria ruziziensis, Pennisetum glaucum and B. ruziziensis + Cajanus cajan and a fallow treatment as reference. Biomass production and the rates of soil cover and nutrient accumulation and release by cover crops as well as rice and soybean yield were evaluated. B. ruziziensis and B. ruziziensis + C. cajan performed best in biomass production, ground cover and nutrient accumulation at the end of the cover crops. The nutrients N and K had the highest concentration in the biomass, and the highest nutrient release to the soil was observed for K and P. The highest rice yield was observed when grown in no-tillage on crop residues of P. glaucum and B. ruziziensis, while soybean yields did not differ in the treatments.
  • 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:
    • Pes, L. Z.
    • Amado, T. J. C.
    • La Scala Jr., N.
    • Bayer, C.
    • Fiorin, J. E.
  • Source: Soil & Tillage Research
  • Volume: 117
  • Year: 2011
  • Summary: The physical protection of mineralizable carbon (C) in aggregates has been identified as the primary mechanism of soil C stabilization. Therefore, it is possible to hypothesize that the disruption of aggregate by soil tillage is a key process driving C losses during the crop-establishment period. However, these findings are based on studies performed in temperate soils. Limited information is available for studies performed in subtropical and tropical soils, especially in Oxisols, which are rich in oxides that provides chemical C stabilization. This study was performed in southern Brazil in a long-term soil-management experiment carried out in a clay Typic Haplorthox in Cruz Alta (RS). During the 22nd year of the experiment, carbon dioxide (CO2-C) emissions, temperature, and soil moisture were intensively evaluated over a 21-day summer crop-establishment period using a closed infrared CO2-flux chamber. The cropping system investigated was an intensive crop rotation following the soil input of winter-cover crops (black oat (Avena strigosa Schreb) + common vetch (Vicia sativa L) under two contrasting tillage systems, conventional tillage (CT) and no-till (NT). The apparent contributions to CO2-C losses by resident soil C associated with aggregate disruption and recent crop-residue C input were assessed in treatments with crop-residue input (+R) and with crop-residue removed (-R). An exponential-decay model was used to fit the differences in CO2-C flux between CT - R and NT - R (apparent aggregate-disruption effect) and between CT + R and CT - R (apparent recent crop-residue C input effect). As expected, the CT + R showed an increase of 72% in CO2-C losses relative to NT + R. During the three-week crop-establishment period, crop-residue C input was the primary source of CO2-C emissions under CT. The CO2-C losses under CT were equivalent to 65% of the aboveground C input by winter cover crops, whereas this value decreased to 35% in NT. Exponential-decay modeling of the data for the first week showed that approximately 20% of the CO2-C losses under CT were related to the exposure of mineralizable resident soil C due by tillage operations. The analysis showed that this value decreased to only 2% for the three-week period. The CO2-C emissions exhibited a positive linear relationship with soil temperature and soil water-filled porosity under NT, but a similar relationship was found only with soil temperature under CT. For this Oxisol during the crop-establishment period, the physical aggregate disruption induced by long-term CT played a secondary role in CO2-C losses relative to the recent crop-residue C input from tillage operations.
  • 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:
    • Santos, H.
    • Fontaneli, R.
    • Spera, S.
    • Dreon, G.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 6
  • Issue: 3
  • Year: 2011
  • Summary: Soil fertility attributes were evaluated on a typical dystrophic Red Latosol (typic Haplorthox) located in Passo Fundo, State of Rio Grande do Sul, Brazil, twelve years after the establishment (1993, 2000, 2002 and 2005) of five integrated crop/livestock farming production systems: system I - wheat/soybean, white oat/soybean, and common vetch/corn; system II - wheat/soybean, white oat/soybean, and grazed black oat+grazed common vetch/corn; system III - perennial cool season pastures (fescue+white clover+red clover+birds foot trefoil); system IV - perennial warm season pastures (bahiagrass+black oat+rye grass+white clover+red clover+birds foot trefoil); and system V - alfalfa as hay crop. The plots under systems III, IV, and V returned to system I after the summer of 1996. However, in the summer of 2002, in the systems III, IV and V, what used to be crop returned to pasture and what used to be pasture returned to crop. An acidification process occurred in all layers by the lowest pH values and higher concentration and saturation by Al, in comparison to the soil in 1998. The organic matter level and the P, K and Al levels increased between 1998 to 2002, in all sampled layers, while the opposite occurred with pH, Ca and Mg contents.
  • Authors:
    • Pauletti, V.
    • Piva, J.
    • Santos, N.
    • Dieckow, J.
    • Bayer, C.
    • Molin, R.
    • Favaretto, N.
  • Source: Soil & Tillage Research
  • Volume: 111
  • Issue: 2
  • Year: 2011
  • Summary: To improve C sequestration in no-till soils requires further development of crop rotations with high phytomass-C additions. The objectives of this study were (i) to assess long-term (17 years) contributions of cover crop- or forage-based no-till rotations and their related shoot and root additions to the accumulation of C in bulk and in physical fractions of a subtropical Ferralsol (20-cm depth); and (ii) infer if these rotations promote C sequestration and reach an eventual C saturation level in the soil. A wheat ( Triticum aestivum L., winter crop)-soybean ( Glycine max (L.) Merr, summer crop) succession was the baseline system. The soil under alfalfa ( Medicago sativa L., hay forage) intercropped every three years with maize ( Zea mays L., summer crop) had the highest C accumulation (0.44 Mg C ha -1 year -1). The bi-annual rotation of ryegrass ( Lolium multiflorum Lam., hay winter forage)-maize-ryegrass-soybean had a soil C sequestration of 0.32 Mg C ha -1 year -1. Among the two bi-annual cover crop-based rotations, the vetch ( Vicia villosa Roth, winter cover crop)-maize-wheat-soybean rotation added 7.58 Mg C ha -1 year -1 as shoot plus root and sequestered 0.28 Mg C ha -1 year -1. The counterpart grass-based rotation of oat ( Avena strigosa Schreb., winter cover crop)-maize-wheat-soybean sequestered only 0.16 Mg C ha -1 year -1, although adding 13% more C (8.56 Mg ha -1 year -1). The vetch legume-based rotation, with a relative conversion factor (RCF) of 0.147, was more efficient in converting biomass C into sequestered soil C than oat grass-based rotation (RCF=0.057). Soil C stocks showed a close relationship ( R2=0.72-0.98, P<0.10) with root C addition, a poor relationship with total C addition and no relationship with shoot C addition. This suggests a more effective role of root than shoot additions in C accumulation in this no-till soil. Most of the C accumulation took place in the mineral-associated organic matter (71-95%, in the 0-5 cm layer) compared to the particulate organic matter. The asymptotic relationship between root C addition and C stocks in bulk soil and in mineral-associated fraction supports the idea of C saturation. In conclusion, forages or legume cover crops contribute to C sequestration in no-till tropical Ferrasols, and most of this contribution is from roots and stored in the mineral-associated fraction. This combination of soil and rotations can reach an eventual soil C saturation.
  • Authors:
    • Scherer, E. E.
  • Source: Agropecuaria Catarinense
  • Volume: 24
  • Issue: 2
  • Year: 2011
  • Summary: Organic agriculture in no-till system requires a new set of producer skills especially in the area of soil fertility and fertilizer use. In a field experiment in organic system in Chapeco, SC, Southern Brazil, the effect of different organic fertilizers (poultry dry litter, swine deep litter, swine composted manure, cattle composted manure and liquid swine manure) on the corn and common been yields was investigated. The organic fertilizers were scattered on the soil surface in the no-till system on the day of the sowing of common bean and corn. The solid manure was applied at 5 and 10 t/ha, dry weight, and the liquid manure at 30 and 60 m 3/ha for common beans and corn, respectively. A completely randomized block experimental design with six replications was used. The utilization of solid and liquid organic manure increased the grain yield of both cultures in all six years. Common beans and corn grain average yield with organic fertilizers use was 30% and 54% greater than yield without fertilizer, respectively. Solid swine manure and organic compost had a better performance on common bean grain yield, and liquid swine manure on corn yield.
  • 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.