• Authors:
    • Mielniczuk, J.
    • Vezzani, F. M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 35
  • Issue: 1
  • Year: 2011
  • Summary: Soil functions and quality are closely linked to soil structure. The effect of management practices on the recovery of the aggregation of a physically degraded soil was studied based on the distribution of water-stable aggregates and single particles (diameter classes 9.51-4.76, 4.76-2.00, 2.00-0.25, 0.25-0.053, <0.053 mm) and carbon stock (C) in the surface layer (0-7.5 cm) of a Paleudult in the Central Depression region of the state of Rio Grande do Sul, Brazil, under different management systems. The following systems were evaluated in experimental plots after 17 years: soil without plants and without tillage (fallow); no-till Lablab purpureus and maize ( Zea mays) (Lablab/m); no-till Cajanus cajan (pea/m) and maize; perennial pasture of Digitaria decumbens (Pangola grass). The following systems were evaluated after 15 years: conventional tillage and no-till Avena strigosa and maize (CT a/m and NT a/m, respectively) Avena strigosa+ Vicia sativa and maize+ Vigna unguiculata (CT av/μ and NT av/mu, respectively). A conventionally tilled area was also evaluated after 30 years of grain cultivation (crop) and native grassland (NGr), representing the degraded state and the native ecosystem of this soil, respectively. Undisturbed soil samples collected in two seasons (September 1999 to September 2000) were evaluated in six replications per management system. Data were analyzed by ANOVA and Tukey's test (5%) to detect differences between management systems. In the NGr, 76.4% of the soil aggregates consisted of 63.8% macroaggregates and of 23.6% of single particles, and a C stock of 20.0 Mg ha -1. The agricultural use with intense soil tillage and low residue application (crop) reduced the proportion of soil aggregates to 49.9% and raised single particles to 50.1%, while the C stock decreased to 11.8 Mg ha -1. From this condition, 15 years of the untilled system with greater diversity of plant species and high residue application (NT av/mc) raised the proportion of soil aggregates to 70.7% and of macroaggregates to 53.5%. Perennial pasture (Pangola) increased the proportion of soil aggregates to 74.1% and of macroaggregates to 61.8%, equaling NGr. The systems NT av/mc, pea/m and Lablab/m recovered C stocks to the level of NGr. Although Pangola had the highest soil aggregation rates, the C stock was lower than in the said systems, emphasizing the positive action of a dense root system in the recovery of soil aggregation.
  • Authors:
    • Edwards, J.
    • Godsey, C.
    • Vitale, J. D.
    • Taylor, R.
  • Source: Journal of Soil and Water Conservation
  • Volume: 66
  • Issue: 4
  • Year: 2011
  • Summary: Conservation tillage had initial roots in the Great Plains, but the current adoption of conservation tillage, especially no-till, lags behind in the rest of the United States. This paper documents the results of a recent survey of Oklahoma producers, which was conducted to assess the current status of conservation tillage in the state. Based on responses from 1,703 producers, econometric analysis was conducted to identify factors explaining the observed use of conservation tillage practices in Oklahoma. The survey found that conventional tillage remains the most common tillage practice among Oklahoma producers. According to the survey, conventional tillage is used on 43.2% of the state's total acreage, conservation tillage on 26.7% of the total acreage, and reduced tillage on the remaining 30.1% of the crop acreage. A Tobit model was developed to explain patterns of tillage use based on producer characteristics and their perceptions on how conservation tillage performs relative to conventional tillage according to various economic and agronomic factors. The Tobit model identified operator age, farm size, crop rotation, knowledge, and erosion control as highly significant factors explaining the observed use of conservation tillage. The model results also identified potential constraints to conservation tillage adoption and use in the Southern Plains, suggesting that the unique needs of mixed crop-livestock farming systems, and the dominant winter wheat ( Triticum aestivum L.) monoculture, hinder further diffusion of conservation tillage. Future policy should consider addressing the needs of Oklahoma producers, particularly crop producers heavily engaged in livestock activities, as well as finding viable rotation crops to provide alternatives for the winter wheat monoculture.
  • Authors:
    • Cai, D.
    • Deng, X.
    • Zhao, Q.
    • Wu, X.
    • Wang, X.
  • Source: Scientia Agricultura Sinica
  • Volume: 44
  • Issue: 11
  • Year: 2011
  • Summary: Changes in land use, especially in cropland-use management, induced by human activities is one of the most important factors influencing climate change. In China, facing the huge pressure of dealing with climate change, the research on the relations between cropland-use management and soil carbon (C) sink, and the effects of cropland-use management on soil C sequestration and C emission mitigation is important, aiming at providing a decision-making basis for improvement of soil C sequestration and C emission mitigation in China. Through the literature reviews, this paper analyzes the impact of cropland-use management on soil C sequestration and C emission mitigation in China. As literature reviewed, agriculture is not only a main source of C emission, but also a sink of C sequestration. Through improvement of cropland-use management (such as increasing straw return into the soil, organic fertilizer application, and no-till/reduced tillage practices, etc.), there has shown an increasing trend in soil C sink in cropland since the last 20 years. Based on the estimation of soil C sequestration in cropland in China, especially with the recommended management practices, especially in the future 50 years, the potential for soil C sequestration in cropland of China is estimated about 87-393 TgC.a -1, thus offsetting about 11%-52% of the total industry C emissions, in which improved cropland-use management (including straw return, organic fertilizer application, and no-till/reduced tillage) could share about 30%-36% of C sequestration. This shows that cropland-use management in China could play an important role in soil C sequestration and C emission mitigation.
  • Authors:
    • Wu, Z. J.
    • Zhu, A. N.
    • Chen, L. J.
    • Chen, Z. H.
    • Wang, J. B.
  • Source: Plant, Soil and Environment
  • Volume: 57
  • Issue: 6
  • Year: 2011
  • Summary: The effects of tillage and residue input amounts on soil phosphatase (alkaline phosphomonoesterase ALP, acid phosphomonoesterase ACP, phosphodiesterase PD, and inorganic pyrophosphatase IPP) activities and soil phosphorus (P) forms (total P, organic P, and available P) were evaluated using soils collected from a three-year experiment. The results showed that no-till increased soil total and organic P, but not available P as compared to conventional tillage treatments. Total P was increased as inputs of crop residue increased for no-till treatment. There were higher ALP and IPP activities in no-till treatments, while higher PD activity was found in tillage treatments and tillage had no significant effect on ACP activity. Overall phosphatase activities increased with an increase of crop residue amounts. Soil total P was correlated negatively with PD activity and positively with other phosphatase activities. Organic P had a positive correlation with ACP activity, but a negative correlation with PD activity. Available P had no significant correlation with phosphatase activities. Our data suggests that no-till and residue input could increase soil P contents and enhance the activities of phosphatase.
  • Authors:
    • Hubbell, D. S.,III
    • Anders, M. M.
    • Beck, P. A.
    • Hignight, J. A.
    • Watkins, K. B.
    • Gadberry, S.
  • Source: Journal of Soil and Water Conservation
  • Volume: 66
  • Issue: 1
  • Year: 2011
  • Summary: Grazing cattle on winter wheat is a common income-generating practice in the Southern Great Plains, but few Arkansas cattle producers utilize this practice. Many areas in the state with potential to benefit from this practice are highly erodible, and conservation tillage may be needed to best ensure the existing natural resource base is not degraded over time. This study evaluates the profitability and return variability of grazing stocker steers on conservation tillage winter wheat pasture using simulation and stochastic dominance analysis. Average daily gains are simulated for steers grazed on conventional tillage, reduced tillage, and no-till winter wheat pasture using seven years of steer weight gain data from a conservation tillage winter wheat forage study near Batesville, Arkansas. Steer prices and prices for key forage production inputs such as diesel, fertilizer, and glyphosate are also simulated to account for their stochastic impacts on return variability. Steer net return distributions are generated for each tillage system, and first and second degree stochastic dominance are used to rank each tillage system according to specified producer preferences. The results indicate both conservation tillage systems are more profitable and less risky than the conventional tillage system. The conventional tillage system is dominated by no-till based on first degree stochastic dominance and by reduced tillage based on second degree stochastic dominance. Thus both conservation tillage systems would be preferred by risk-averse cattle producers to the conventional tillage system based on this analysis.
  • Authors:
    • Torbert, H. A.
    • Watts, D. B.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: Reduced tillage, poultry litter applications, crop rotations, and winter cover cropping are management practices that could be used with conservation tillage systems to increase yields compared to conventional monoculture systems. This study evaluated cropping sequences of corn ( Zea mays L.), soybean [ Glycine max (L.) Merr.], and corn-soybean rotations with wheat ( Triticum aestivum L.) covers in conventional, strip, and no-tillage (no-till) systems, following poultry litter additions to wheat cover. The study was conducted from 1991 to 2001 on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Poultry litter (112 kg N ha -1) was applied to wheat each year in fall. Wheat not receiving poultry litter received equivalent inorganic N. Corn was fertilized with inorganic fertilizer in spring with 56 kg N ha -1 at planting followed by 168 kg N ha -1 3 wk after emergence; soybean received no fertilizer. Corn yields were influenced by tillage in 1991, 1992, 1993, 1994, 1996, 1997, 1998, and 2001 with conventional tillage producing greater yields, except in 1993 (strip tillage) and 2001 (no-till). Poultry litter increased corn yield in 1991, 1997, and 1998. Crop rotations increased corn yield for all years, except 2001. Soybean yields were not impacted by differences in tillage. Crop rotations significantly impacted soybean yield in 1992, 1995, and 1998, with higher yields observed in 1992, and 1995, and lower yields in 1998. Poultry litter significantly increased soybean yield 8 of the 9 yr evaluated. This study suggests that poultry litter use for these crop rotations in conservation tillage systems could increase sustainable yield production.
  • Authors:
    • Miller, P.
    • Lawrence, R. L.
    • Watts, J. D.
    • Montagne, C.
  • Source: Climactic Change
  • Volume: 108
  • Issue: 1/2
  • Year: 2011
  • Summary: A pilot cropland carbon sequestration program within north central Montana has allowed farmers to receive carbon credit for management adjustments associated with changing from tillage-based agricultural systems to no-till. Carbon credit can also be obtained by adopting conservation reserve, where cropland is planted into perennial vegetation. Summer fallowing is also considered within the crediting process as credit is not given in years that a field is left un-vegetated. The carbon sequestration program has been advocated as a means to mitigate climate change while providing an added source of income for Montana farmers. There is lack of data, however, pertaining to the percentage of lands within this region that have not converted to no-till management, lands under certain crop intensities (e.g. those that are cropped every growing season vs. those that use a fallow-crop-fallow system), or cropland that have converted to perennial vegetation outside of the popular Conservation Reserve Program. Data is also sparse concerning the amount of soil organic carbon that might be sequestered given a conversion to no-till or conservation reserve. This study established regional percentage estimates of cropland under no-till, various degrees of crop intensity, and conservation reserve within north central Montana. Literature-based carbon sequestration estimates were used to generate carbon gain data associated with the conversation to no-till and to conservation reserve. These estimates were then applied to the area-based cropland statistics to estimate potential regional carbon sequestration associated with these management changes.
  • Authors:
    • Hilker, T.
    • Lawrence, R. L.
    • Powell, S. L.
    • Watts, J. D.
  • Source: Remote Sensing of Environment
  • Volume: 115
  • Issue: 1
  • Year: 2011
  • Summary: Conservation tillage management has been advocated for carbon sequestration and soil quality preservation purposes. Past satellite image analyses have had difficulty in differentiating between no-till (NT) and minimal tillage (MT) conservation classes due to similarities in surface residues, and may have been restricted by the availability of cloud-free satellite imagery. This study hypothesized that the inclusion of high temporal data into the classification process would increase conservation tillage accuracy due to the added likelihood of capturing spectral changes in MT fields following a tillage disturbance. Classification accuracies were evaluated for Random Forest models based on 250-m and 500-m MODIS, 30-m Landsat, and 30-m synthetic reflectance values. Synthetic (30-m) data derived from the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) were evaluated because high frequency Landsat image sets are often unavailable within a cropping season due to cloud issues. Classification results from a five-date Landsat model were substantially better than those reported by previous classification tillage studies, with 94% total and >= 88% class producer's accuracies. Landsat-derived models based on individual image scenes (May through August) yielded poor MT classifications, but a monthly increase in accuracy illustrated the importance of temporal sampling for capturing regional tillage disturbance signatures. MODIS-based model accuracies (90% total; >= 82% class) were lower than in the five-date Landsat model, but were higher than previous image-based and survey-based tillage classification results. Almost all the STARFM prediction-based models had classification accuracies higher than, or comparable to, the MODIS-based results (>90% total; >= 84% class) but the resulting model accuracies were dependent on the MODIS/Landsat base pairs used to generate the STARFM predictions. Also evident within the STARFM prediction-based models was the ability for high frequency data series to compensate for degraded synthetic spectral values when classifying field-based tillage. The decision to use MODIS or STARFM-based data within conservation tillage analysis is likely situation dependent. A MODIS-based approach requires little data processing and could be more efficient for large-area mapping; however a STARFM-based analysis might be more appropriate in mixed-pixel situations that could potentially compromise classification accuracy.
  • Authors:
    • Bortniak, M.
    • Goebiowska, H.
    • Weber, R.
  • Source: Journal of Plant Protection Research
  • Volume: 51
  • Issue: 4
  • Year: 2011
  • Summary: The objective of the study was to analyse the variability of the weed infestation of several winter wheat cultivars in relation to the soil tillage system applied and to the height of preceding crop stubble. The study was conducted in the years 2008-2010 in Lower Silesia, Poland. The following factors were studied in the experiment: factor I - stubble height a/ short stubble (10 cm) b/ tall stubble (40 cm); factor II - soil tillage systems a/ no-till b/ reduced tillage c/ conventional tillage - ploughing; factor III - winter wheat cultivars a/ Mewa, b/ Rapsodia, c/ Legenda. After the harvest of the preceding crop, glyphosate was sprayed on plots with short and tall stubble, in the first 10-days of August. The number of weeds on each analysed plot was estimated at random, with the frame method. For statistical analysis, the 8 most frequent weed species were selected: Viola arvensis, Sinapsis arvensis, Lamium purpureum, Veronica persica, Apera spica-venti, Capsella bursa-pastoris, Anthemis arvensis and Geranium pusillum. Based on the log-linear analysis, it was determined that V. arvensis and S. arvensis w ere the dominant weed species, whereas A. spica-venti and C. bursa-pastoris were characterised by significantly smaller numbers per 1 m 2. Significantly greater weed infestation was observed on plots with tall stubble. Increased weed infestation of winter wheat was noted in the reduced tillage treatments compared to those with conventional tillage. Only the numbers of S. arvensis were considerably lower under the conditions of no-till than in the conventional or reduced tillage systems. Cultivar Mewa limited the number of weeds per unit of area to a significant degree, while cv. Legenda increased weed infestation.
  • Authors:
    • Corp, M.
    • Wuest, S.
  • Source: Crop Management
  • Issue: December
  • Year: 2011
  • Summary: Millions of acres of cropland with as low as 6 inches annual precipitation are used for production of winter wheat ( Triticum aestivum L.) in the Pacific Northwest of the USA. Despite soil conservation advances, soil erosion continues to be a problem. This on-farm study analyzed seed-zone soil water under farmer-implemented fallow tillage practices to find out if very low-disturbance systems are possible. A low-disturbance, wide-blade undercutter sweep treatment was similar or superior to the farmer's more intensive conventional tillage system. A subsequent test at four paired no-till-conventionally-tilled summer-fallow sites demonstrated that a single pass of an undercutter sweep in the no-till field could preserve seed-zone moisture comparable to the more intensive multiple-pass conventional tillage. Despite conventional wisdom, summer-fallow soil mulches do not need to be finely pulverized or repeatedly tilled to be effective.