• Authors:
    • Humburg, D. S.
    • Schumacher, T. E.
    • Osborne, S. L.
  • Source: Agricultural Journal
  • Volume: 3
  • Issue: 5
  • Year: 2008
  • Summary: Although no-till soil management has many benefits, including protecting the soil from erosion, improving soil organic matter and improving soil moisture storage, depending on environmental conditions there could be a number of potential problems. Implementation of no-till soil management in eastern South Dakota can lead to wet and cold soils at the time of planting. Cover crops have the potential to utilize excess soil moisture and improve soil conditions at planting. A field experiment was established to evaluate the impact of 14 different cover crop species as well as no cover crop and conventional tillage on soil conditions prior to corn planting and the impact on corn yield and quality. The experimental design was a randomized complete block design with 4 replications. Cover crops evaluated include a mixture of grass, legumes, cool and warm season crops. All cover crops were planted in early August (following spring wheat harvest) at recommended seeding rates. The following spring all plots were planted to corn ( Zea mays L.). The experiment was conducted in a 3 year crop rotation (soybean [ Glycine max (L.) Merrill]/spring wheat ( Triticum aestivum L.)-cover crop/corn). Cover crop species that survived the winter included hairy vetch, red clover, sweet clover, Alsike clover, slender wheatgrass and winter ryegrass. The presence of these species increased soil strength and reduced soil moisture. Corn grown following hairy vetch was the only treatment that exhibited a significant reduction in plant population. Corn yield for plots grown under red clover, winter ryegrass and no cover crop had yield significantly higher than corn grown after conventional tillage, hairy vetch and slender wheatgrass. This experiment illustrated the ability of cover crops to utilize excess soil moisture and increase soil strength compared to conventional tillage or no cover crop.
  • Authors:
    • Reddy, K. C.
    • Tazisong, I. A.
    • Nyakatawa, E. Z.
    • Senwo, Z. N.
    • Sainju, U. M.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 3
  • Year: 2008
  • Summary: Quantification of soil carbon (C) cycling as influenced by management practices is needed for C sequestration and soil quality improvement. We evaluated the 10-yr effects of tillage, cropping system, and N source on crop residue and soil C fractions at 0-to 20-cm depth in Decatur silt loam (clayey, kaolinitic, thermic, Typic Paleudults) in northern Alabama, USA. Treatments were incomplete factorial combinations of three tillage practices (no-till [NT], mulch till [MT], and conventional till [CT]), two cropping systems (cotton [Gossypium hirsutum L.]-cotton-corn [Zea mays L.] and rye [Secale cereale L.]/cotton-rye/cotton-corn), and two N fertilization sources and rates (0 and 100 kg N ha(-1) from NH4NO3 and 100 and 200 kg N ha(-1) from poultry litter). Carbon fractions weresoil organic C (SOC), particulate organic C (POC), microbial biomass C (MBC), and potential C mineralization (PCM). Crop residue varied among treatments and years and total residue from 1997 to 2005 was greater in rye/cottoil-rye/cotton-corn than in cotton-cotton-corn and greater with NH4NO3 than with poultry litter at 100 kg N ha(-1). The SOC content at 0 to 20 cm, after 10 yr was greater with poultry litter than with NH4NO3 in NT and CT, resulting in a C sequestration rate of 510 kg C ha(-1) yr(-1) with poultry litter compared with -120 to 147 kg C ha(-1) yr(-1) with NH4NO3. Poultry litter also increased PCM and MBC compared with NH4NO3. Cropping increased SOC, POC, and PCM compared with fallow in NT Long-term poultry litter application or continuous cropping increased soil C storage and microbial biomass and activity compared with inorganic N fertilization or fallow, indicating that these management practices can sequester C, offset atmospheric CO2 levels, and improve soil and environmental quality.
  • Authors:
    • Schlindwein, J. A.
    • Gianello, C.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 32
  • Issue: 5
  • Year: 2008
  • Summary: The change of cultivation systems from conventional to no-tillage, the change in soil sampling depth and the higher crop yields over time can influence the critical P content, fertility ranges and fertilizer doses recommended for crops. This study calibrated the soil P tests, Mehlich-1, Mehlich-3 and anion-exchange (AER) resin for soyabean, wheat and maize plants cultivated under no-tillage system, and to estimate the P fertilizer amounts for a maximum economic yield. Soil samples and yield results from several experiments under no-till and different P doses, conducted by institutions of education, research and extension of the state of Rio Grande do Sul, Brazil, were used. The calibration curves were fitted using non-linear model functions, and the levels of soil fertility and fertilizer doses for a maximum economic yield were inferred. Results indicated that the average increases in maize, wheat and soyabean yields were 47.1, 12.4 and 7.2 kg/ha per kg of P 2O 5, respectively; the determination coefficients between the relative yield and soil P concentrations were higher when the soils were separated by texture classes and were highest in the 0-10 cm than the 0-20 cm layer; the critical values of P, based on Mehlich-1 were 7.5, 15.0 and 21.0 mg/kg in the 0-20 cm layer, and of 16.0, 28.0 and 40.0 mg/kg in the 0-10 cm layer in the clay classes 1, 2 and 3, respectively. Phosphorus fertility ranges were wider by Mehlich-3 and AER as compared to Mehlich-1. The quantities of P fertilizer were higher for soyabean and maize when compared to the currently recommended quantities. The critical P concentrations are higher in soils under no-tillage with soyabean, wheat and maize in the 0-20 as well as the 0-10 cm layer. The fertility ranges by resin and Mehlich-3 were wider than by Mehlich-1. The fertilizer P quantities are higher for soyabean and maize grown under no-tillage.
  • Authors:
    • Alves, M. C.
    • Arf, O.
    • Silva, M. G. da
    • Buzetti, S.
  • Source: Bragantia
  • Volume: 67
  • Issue: 2
  • Year: 2008
  • Summary: The soil physical properties are influenced by different soil tillage as well as by crop rotation. Field studies were conducted in Selviria, Mato Grosso do Sul, Brazil, in 2003/04, to evaluate the shoot dry matter production, soil covering percentage and the influence of crop rotation and tillage system on soil physical properties of a Rhodic Hapludox and to evaluate irrigated winter common bean yield. The treatments consisted of soil tillage systems (heavy harrow, chisel plough and no-tillage) and 6 rotations sown in the summer (maize, maize + black velvet bean, maize + brachiaria grass, soyabean, rice and sunn hemp). The crop rotations that presented larger soil coverage and shoot dry matter production were sunn hemp, maize + black velvet bean, maize + braquiaria grass and maize. No-tillage resulted in larger values of penetration resistance at 0.00-0.10 m layer. Except for macroporosity at the 0-0,1 m layer, the properties humidity, macroporosity, microporosity and total porosity of soil were not influenced by soil tillage systems. Despite differences in some yield components of common bean due to certain soil tillage or crop succession, the irrigated winter common bean crop yield was not affected.
  • Authors:
    • Follett, R. F.
    • Alley, M. M.
    • Spargo, J. T.
    • Wallace, J. V.
  • Source: Soil & Tillage Research
  • Volume: 100
  • Issue: 1/2
  • Year: 2008
  • Summary: Carbon sequestration in agroecosystems represents a significant opportunity to offset a portion of anthropogenic CO 2 emissions. Climatic conditions in the Virginia coastal plain and modern production practices make it possible for high annual photosynthetic CO 2 fixation. There is potential to sequester a substantial amount of C, and concomitantly improve soil quality, with the elimination of tillage for crop production in this region. The objectives of our research were to: (1) measure C sequestration rate with continuous no-till management of grain cropping systems of the Virginia middle coastal plain; (2) determine the influence of biosolids application history on C content and its interaction with tillage management; and (3) evaluate the impact of continuous no-till C stratification as an indicator of soil quality. Samples were collected from 63 sites in production fields using a rotation of corn ( Zea mays L.)-wheat ( Triticum aestivum L.) or barley ( Hordeum vulgare L.)/soybean double-crop ( Glysine max L.) across three soil series [Bojac (coarse-loamy, mixed, semiactive, thermic Typic Hapludults), Altavista (fine-loamy, mixed semiactive, thermic Aquic Hapludults), and Kempsville (fine-loamy, siliceous, subactive, thermic Typic Hapludults)] with a history of continuous no-till management ranging from 0 to 14 years. Thirty-two of the sites had a history of biosolids application. Five soil cores were collected at each site from 0-2.5, 2.5-7.5 and 7.5-15 cm and analyzed for bulk density and soil C. Bulk density in the 0-2.5 cm layer decreased and C stratification ratio (0-2.5 cm:7.5-15 cm) increased with increasing duration of continuous no-till due to the accumulation of organic matter at the soil surface. A history of biosolids application resulted in an increase of 4.191.93 Mg C ha -1 (0-15 cm). Continuous no-till resulted in the sequestration of 0.3080.280 Mg C ha -1 yr -1 (0-15 cm). Our results provide quantitative validation of the C sequestration rate and improved soil quality with continuous no-till management in the region using on-farm observations.
  • Authors:
    • Suzuki, L. G. A. S.
    • Alves, M. C.
    • Suzuki, L. E. A. S.
    • Rodrigues, R. A. F.
  • Source: Científica, Jaboticabal
  • Volume: 36
  • Issue: 2
  • Year: 2008
  • Summary: The objective of this study was to verify the biomass yield potential of different cover crops in a Cerrado region, in Selviria, Mato Grosso do Sul, Brazil. The work was conducted in the Experimental University Farm of the Paulista State University (UNESP). The experimental design was the randomized complete blocks in strips with splitsplit plot: the plots were the cover crops Mucuna aterrima, Pennisetum americanum, Crotalaria juncea, Cajanus cajan and a fallow area; the split plots were the no-tillage and the conventional tillage, and the splitsplit plots were corn ( Zea mays L.), soybean ( Glycine max (L.) Merrill), and cotton ( Gossypium hirsutum L.) crops. In the winter irrigated Phaseolus vulgaris L. was the crop. In the spring/summer season the cover crop with the greatest biomass yield was Pennisetum americanum. Crotalaria juncea and the fallow area showed medium results while Mucuna aterrima and Cajanus cajan were those with the least yields. Pennisetum americanum was the crop cover with the biggest production potential of dry biomass. The cultivation systems did not influence the dry biomass of the cover crops. Only Pennisetum americanum production was influenced by crop sequence.
  • Authors:
    • Santini, J. B.
    • Vyn, T. J.
    • Faghihi, J.
    • Ferris, V. R.
    • Westphal, A.
    • Creech, J. E.
    • Johnson, W. G.
  • Source: Weed Science
  • Volume: 56
  • Issue: 1
  • Year: 2008
  • Summary: Certain winter annual weeds have been documented as alternative hosts to soybean cyst nematode (SCN), and infestations of such species have become common in no-till production fields in the Midwest. This research was conducted to determine the influence of herbicide- and cover-crop-based winter annual weed management systems and crop rotation on winter annual weed growth and seed production, SCN population density, and crop yield. Two crop rotations (continuous soyabean and soyabean-maize) and six winter annual weed management systems (a nontreated control, autumn and spring herbicide applications, spring-applied herbicide, autumn-applied herbicide, autumn-sown annual ryegrass, and autumn-sown winter wheat) were evaluated in no-tillage systems from autumn 2003 to 2006 at West Lafayette and Vincennes, Indiana. Autumn or spring herbicide treatments generally resulted in lower winter annual weed densities than cover crops. Densities of henbit and purple deadnettle increased over years in the cover crop systems but remained constant in the herbicide systems. Averaged over sites and years, winter annual weed densities were nearly 45% lower in the spring than the autumn due to winter mortality. Maize yield was reduced by the cover crops at West Lafayette but not Vincennes. Winter annual weed management system had no influence on soyabean yield. SCN population density was reduced by including maize in the crop sequence but was not influenced by winter annual weed management. The density of weedy host species of SCN in the experimental area was relatively low (less than 75 plants m -2) compared to densities that can be observed in production fields. The results suggest that inclusion of maize into a cropping sequence is a much more valuable SCN management tool than winter annual weed management. In addition, control of winter annual weeds, specifically for SCN management, may not be warranted in fields with low weed density.
  • Authors:
    • Barbottin, A.
    • Colbach, N.
    • Gruber, S.
    • Pekrun, C.
  • Source: CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources
  • Volume: 3
  • Issue: 015
  • Year: 2008
  • Summary: Data about gene escape by seeds and volunteers were compiled for the first time in one study for several crops, i.e. wheat ( Triticum aestivum), sugar beet ( Beta vulgaris), oilseed rape/canola ( Brassica napus) and maize ( Zea mays). These species represent important genetically modified (GM) crops with herbicide tolerance (HT) or insect resistance (Bt), show different levels of autogamy and allogamy and are grown in different climatic zones of the world. Post-harvest measures and strategies were identified for minimizing gene escape from these crops. All species were found to cause problems in terms of gene escape by seed and volunteers though there are important differences between species and climatic zones. Post-harvest tillage was identified as a key factor for reducing the soil seed bank and volunteers. Timing and intensity of tillage has to be specifically adapted to the dormancy characteristics of each species. Furthermore, there is a close interaction between gene escape and the cropping system. Rotations should avoid the same crop or other critical crops in temporal vicinity to the GM crop in order to keep volunteer populations below a critical density. In no-till systems with use of HT varieties, HT volunteers can reduce the efficiency of the whole system if additional herbicides have to be applied. Seed impurities and admixtures during seed production are another major source of gene escape. Since seed lots of certified growers present less adventitious presence of other varieties, these should be preferred to farm-saved seeds. Education of farmers, cleaning of equipment, control measures and separate production and supply chains are additionally important to minimize gene escape.
  • 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:
    • Tang, L.
    • Tang, C. Z.
    • Guan, C. Y.
    • Wu, M. L.
  • Source: Journal of Hunan Agricultural University (Natural Sciences)
  • Volume: 34
  • Issue: 6
  • Year: 2008
  • Summary: Due to its insufficient intensity, with the target of minimizing its mass, an optimum model for disk of ditching knives of type 2BYF-6 rape combine seeder was established on a permissible condition of intensity. Wit the use of the Matlab software, the parameters after optimization are as follows: the inner hole diameter of the ditching knives disk is 50 mm, the number of knives is 6, the thickness of knives disk is 6 mm, the location dimension of the bolt on knife was 360 mm, and the mass of the knives disk after optimization reduced by 10%. Field test indicated, after optimization, the malfunction per hour of the product was reduced by 200%.