• Authors:
    • Wuest, S. B.
    • Siemens, M. C.
    • Gollany, H. T.
    • Williams, J. D.
    • Long, D. S.
  • Source: Journal of Soil and Water Conservation
  • Volume: 64
  • Issue: 1
  • Year: 2009
  • Summary: Conservation tillage systems that reduce Soil erosion and maintain or increase soil carbon offer long-term benefits for producers in the inland Pacific Northwestern United States but Could result in reduced grain yields due to increased pressure from weeds, disease, and insect pests. Our objective was to compare runoff, soil erosion, and crop yields from a conventional tillage, wheat-fallow two-year rotation and a no-till four-year rotation. The experiment was undertaken within a small,watershed to provide results that would be representative of conservation effectiveness at the field scale. Two neighboring drainages, 5.8 and 10.7 ha (14 and 26 ac), in the 340 mm y(-1) (13.4 in yr(-1)) precipitation zone of northeastern Oregon, were instrumented to record rainfall, runoff, and erosion over a four-year period (2001 through 2004). One drainage was cropped to a winter wheat-fallow rotation and received inversion tillage (tillage fallow). The second drainage was cropped in a four-year no-till rotation: winter wheat-chemical fallow-winter wheat-chickpea (no-till Fallow). We recorded 13 runoff events from the inversion tillage system and 3 from the no-till system. Total runoff and erosion values from inversion tillage drainage were 5.1 mm (0.20 in) and 0.42 Mg ha(-1) (0.19 tn ac(-1)) versus 0.7 mm (0.03 in) and 0.01 Mg ha(-1) (<0.005 in ac(-1)) from no-till drainage. The no-till rotation was substantially more effective in conserving soil and water in this field-scale comparison. Soil erosion observed in this research is a fraction of that reported for similar tillage practices outside of the Pacific Northwestern. Mean wheat yields did not significantly differ between inversion tillage and no-till treatment despite intensifying the rotation by replacing one year of fallow with a chickpea crop in the four-year rotation. Because of high year-to-year variability in yield and limited sample size, more study is needed to compare winter wheat yields in no-till production systems with inversion tillage. The no-till cropping system was more e effective in reducing runoff and soil erosion and provides producers with an ability to protect soil and water resources in the dryland Pacific Northwest.
  • Authors:
    • Gonzalez, A.
    • Luciano, R.
    • Bertol, I.
    • Barbosa, F.
    • Vazquez, E.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 33
  • Issue: 2
  • Year: 2009
  • Summary: Where nutrients are lost by water erosion, the eroded soil is impoverished and crop productivity is reduced, apart from the water contamination. Soluble N in the runoff is biologically available and contributes to eutrophication of the water and, depending on the form and content in the water, may be toxic to aquatic organisms. In order to evaluate the N content in the form of ammonium and nitrate in the runoff water, an experiment was conducted with simulated rainfall from April to November 2006, on an Inceptisol under conventional tillage. A combination of three factors was studied: crop type, sowing form and simulated rainfall test. The crops black oat ( Avena strigosa) [ Avena nuda] and common vetch ( Vicia sativa) were studied, as well as the sowing forms: mechanical, along rows in slope direction; broadcast by hand; and mechanized along contour lines; and five simulated rainfall tests, at a constant and planned intensity of 64 mm/h and rainfall duration of 1 h. The first four rainfall tests were applied during the crop cycles and the fifth on the crop residues maintained on the soil surface. Nitrogen application to oat as urea cover dressing, immediately before rainfall test 1, resulted in a higher N-NH 4+ content in the runoff water from oat than from vetch, exceeding the acceptable level for the aquatic community. The residues decomposition on the soil surface under rainfall, the content of soluble N-NO 3- in the runoff water was higher in the crops of contour sowing than of slope sowing. The contents of soluble N-NH 4+ and N-NO 3- in the runoff water decreased from the beginning to the end of the crop cycles, but increased in the rainfall test on vetch mulch, to higher values than in the treatment with oat residue.
  • Authors:
    • Zheng, M.
    • Wang, T.
    • Li, Z.
    • Cai, C.
    • Guo, Z.
  • Source: Agroforestry Systems
  • Volume: 76
  • Issue: 1
  • Year: 2009
  • Summary: Land management practices that simultaneously improve soil properties are crucial to high crop production and minimize detrimental impact on the environment. The effects of crop residues on crop performance, the fluxes of soil N 2O and CO 2 under wheat-maize (WM) and/or faba bean-maize (FM) rotations in Amorpha fruticosa (A) and Vetiveria zizanioides (V) intercropping systems on a loamy clay soil, in subtropical China, were examined. Crop performance, soil N 2O and CO 2 as well as some potential factors such as soil water content, soil carbon, soil nitrogen, microbial biomass and N mineralization were recorded during 2006 maize crop cultivation. Soil N 2O and CO 2 fluxes are determined using a closed-based chamber. Maize yield was greater after faba bean than after wheat may be due to differences in supply of N from residues. The presence of hedgerow significantly improved maize grain yields. N 2O emissions from soils with maize were considerably greater after faba bean (345 g N 2O-N ha -1) than after wheat (289 g N 2O-N ha -1). However, the cumulated N 2O emissions did not differ significantly between WM and FM. The difference in N 2O emissions between WM and FM was mostly due to the amounts of crop residues. Hedgerow alley cropping tended to emit more N 2O than WM and FM, in particular A. fruticosa intercropping systems. Over the entire 118 days of measurement, the N 2O fluxes represented 534 g N 2O-N ha -1 (AWM) and 512 g N 2O-N ha -1 (AFM) under A. fruticosa species, 403 g N 2O-N ha -1 (VWM) and 423 g N 2O-N ha -1 (VFM) under Vetiver grass. A significantly higher CO 2 emission was observed in AFM (5335 kg CO 2-C ha -1) from June to October, whereas no significant difference was observed among WM (3480 kg CO 2-C ha -1), FM (3302 kg CO 2-C ha -1), AWM (3877 kg CO 2-C ha -1), VWM (3124 kg CO 2-C ha -1) and VFM (3309 kg CO 2-C ha -1), indicating the importance of A. fruticosa along with faba bean residue on CO 2 fluxes. As a result, crop residues and land conversion from agricultural to agroforestry can, in turn, influence microbial biomass, N mineralization, soil C and N content, which can further alter the magnitude of crop growth, soil N 2O and CO 2 emissions in the present environmental conditions.
  • Authors:
    • Ruiz, J. C.
    • Vanderlinden, K.
    • Melero, S.
    • Madejon, E.
  • Source: The Journal of Agricultural Science
  • Volume: 147
  • Issue: 1
  • Year: 2009
  • Summary: Soil enzyme activities are widely utilized as rapid and sensitive indicators in discriminating among soil management effects. The objective of the present study was to compare the influence of conservation tillage, i.e. direct drilling (DD) (residue cover is left on the soil surface) v. conventional tillage (CT), on soil chemical and biochemical properties in a crop rotation (cereals-sunflower-legumes) under dryland production in a semi-arid Mediterranean Vertisol after 23 years. A randomized experimental design was established. Soil biological status was evaluated by measuring of enzymatic activities (dehydrogenase, beta-glucosidase, alkaline phosphatase and protease). Total organic carbon (TOC) contents were greater in soils managed by DD than those found by CT. Except for protease activity, enzymatic activity values were approximately 2-fold higher in soils under DD than in soils under CT. The beta-glucosidase, alkaline phosphatase and dehydrogenase values showed a high correlation (from r=0.481 to r=0.886, P≤0.01) with TOC contents and they were correlated with each other (from r=0.664 to r=0.923, P≤0.01). The coefficient of variation of biochemical properties was higher than those of chemical properties in both treatments. Principal component analysis (PCA) showed that two principal components explained 58% and 20% of the total variability. The first principal component was influenced mostly by beta-glucosidase, dehydrogenase and TOC, whereas the second was influenced by pH. The first component effectively differentiated managed soil under both agriculture practices. In general, long-term soil conservation management by DD in a dryland farming system improved the quality of this Vertisol by enhancing its organic matter content and biochemical activity.
  • Authors:
    • Lal,R.
    • Dubey,A.
  • Source: Journal of Crop Improvement
  • Volume: 23
  • Issue: 4
  • Year: 2009
  • Summary: Sustainability of agricultural systems depends on their carbon (C) footprint, and the C output:C input ratio. Thus, this study was conducted with the objectives to: (i) assess the agricultural C emissions in relation to predominant farming systems in Punjab, India, and Ohio, USA; (ii) evaluate C-use efficiency of production systems; and (iii) determine the relative sustainability of agronomic production systems as determined by their C footprints. The data collated on C-based input into the soil for predominant crops for both regions included the amounts of fertilizers (N, P, K), herbicides and pesticides used for each crop annually, tillage methods, cropland area, total production of each crop, area under different farming systems, water-management practices (e.g., tubewell irrigation), and total number of livestock. These data were used to compute C equivalent (CE) per hectare of input and output, and the relative sustainability indices as a measure of the C-production efficiency. There existed a linear relationship observed between C input and C output for Punjab, indicating that an increase of 1 Tg/yr (1 Tg=teragram=10 12 g=million ton) of C input resulted in the corresponding C output of ~12 Tg/yr. A similar linear relationship between input and net C output between the 1930s and 1980s was observed for Ohio, and the ratio reached a plateau during 1990s. The average C-sustainability index (increase in C output as % of C-based input) value for Ohio from 1990 to 2005 was 35-43, almost 2.5 times that of Punjab. Since 1989, there has been a major shift in Ohio from conventional tillage to reduced and conservation tillage along with a decline in fertilizer use. No-till farming is practiced on about 35% of the cultivated area, which involves elimination of plowing, retention of crop residue mulch, and judicious use of chemicals. In Punjab, crop residues are removed, resulting in loss of C from the soil organic carbon pool. Hence, the C-based sustainability index is much higher in Ohio than in Punjab. C-efficient systems are more sustainable than inefficient farming systems, and residue removal reduces agricultural sustainability by depleting the soil C pool.
  • Authors:
    • Gotosa, J.
    • Gwenzi, W.
    • Chakanetsa, S.
    • Mutema, Z.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 83
  • Issue: 3
  • Year: 2009
  • Summary: In southern Africa, tillage research has focused on rainfed smallholder cropping systems, while literature on high-input irrigated cropping systems is limited. We evaluated the effects of conventional (CT), minimum (MT) and no-till (NT) tillage systems on soil organic carbon (SOC), bulk density, water-stable aggregates (WSA), mean weighted diameter (MWD) and crop yields in an irrigated wheat-cotton rotation. Soil data were monitored in the first and final year, while yields were monitored seasonally. Average bulk densities (1.5-1.7 Mg m -3) were similar among tillage systems, but often exceeded the critical limit (1.60 Mg m -3) for optimum root growth. Conversion from CT to MT and NT failed to ameliorate the high bulk densities associated with the alluvial soil. SOC (g kg -1) at 0-15 cm was higher ( P<0.05) under MT (3.9-5.8) and NT (4.2-5.6) than CT (2.9-3.3). Corresponding horizon SOC stocks (Mg C ha -1) for the tillage treatments were; 9.3-13.9 (MT), 9.3-13.5 (NT) and 7.3-7.7 (CT). In the final year, significant ( P<0.05) tillage effects on SOC stocks were also observed at 15-30 cm. Cumulative SOC stocks (Mg C ha -1) in the 0-60 cm profile were higher ( P<0.05) under MT (32.8-39.9) and NT (32.9-41.6) than CT (27.8-30.9). On average, MT and NT sequestered between 0.55 and 0.78 Mg C ha -1 year -1 at 0-30 cm depth, but a net decline (0.13 Mg C ha -1 year -1) was observed under CT. At 0-30 cm, MT and NT had higher ( P<0.05) MWD (0.19-0.23 mm) and WSA (2.3-3.5%) than CT (MWD: 0.1-0.12 mm, WSA: ~1.0%). Both MWD and WSA were significantly ( P<0.05) correlated to SOC. Seasonal yields showed significant ( P<0.05) tillage effects, but 6-year mean yields (t ha -1) were similar (CT: 4.49, MT: 4.33, NT: 4.32 for wheat; CT: 3.30, MT: 2.82, NT: 2.83 for cotton). Overall, MT and NT improved soil structural stability and carbon sequestration, while impacts on crop productivity were limited. Therefore, MT and NT are more sustainable tillage systems for the semi-arid regions than conventional tillage.
  • Authors:
    • Scialabba, N.
    • Hepperly, P.
    • Fließbach, A.
    • Niggli, U.
  • Year: 2009
  • Authors:
    • Bauer, P. J.
    • Watts, D. W.
    • Frederick, J. R.
    • Novak, J. M.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 2
  • Year: 2009
  • Summary: Long-term disk tillage (DT) for cotton (Gossypium hirsutum L.) production in the southeastern U.S. Coastal Plain has resulted in soil organic C (SOC) content reductions. Conservation tillage (CT) management in some studies can rebuild SOC levels. A field study, with two adjacent 3.5-ha fields, both containing soil series formed in upland and depressional areas, was conducted using a 6-yr rotation of corn (Zea mays L.) and cotton to determine the CT and DT effects on SOC contents and residue characteristics returned to the soil. Annual soil samples were collected from 50 locations per field at 0- to 3- and 3- to 15-cm. After 6 yr under CT, residue accumulation promoted a significant SOC increase in the 0- to 3-cm depth in the upland soil series (about 0.7 Mg SOC ha(-1)). The lack of residue mixing in the 3- to 15-cm depth in upland Soils under CT however, resulted in a significant SOC content decline at this depth (1.25-2.51 Mg SOC ha(-1)). There was no significant SOC content change in soils under CT formed in depressional areas or in all soils under DT During 6 yr, 14.8 Mg ha(-1) of organic C from both corn and cotton residues was returned to Soils under CT but <4% was incorporated into the SOC pool. Levels of SOC in sandy upland soils can be increased at the surface after 6 yr of CT under a corn and cotton rotation, with the increase coming at the expense of an SOC decline at a deeper topsoil depth.
  • Authors:
    • Fortin, J.
    • Tremblay, G.
    • Ziadi, N.
    • Chantigny, M. H.
    • Rochette, P.
    • Angers, D. A.
    • Poirier, V.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 1
  • Year: 2009
  • Summary: Both tillage and fertilizer management influence soil organic C (SOC) storage, but their interactive effects remain to be determined for various soil and climatic conditions. We evaluated the long-term effects of tillage (no-till, NT, and moldboard plowing, MP), and N and P fertilization on SOC stocks and concentrations in profiles of a clay loam soil (clayey, mixed, mesic Typic Humaquept). Corn (Zea mays L.) and soybean [Glycine max (L) Merr.] were grown in a yearly rotation for 14 yr. Our results showed that NT enhanced the SOC content in the soil surface layer, but MP resulted in greater SOC content near the bottom of the plow layer. When the entire soil profile (0-60 cm) was considered, both effects compensated each other, which resulted in statistically equivalent SOC stocks for both tillage practices. Nitrogen and P fertilization with MP increased the estimated crop C inputs to the soil but did not significantly influence SOC stocks in the whole soil profile. At the 0- to 20-cm depth, however, lower C stocks were measured in the plowed soil with the highest N fertilizer level than in any other treatment, which was probably caused by a greater decomposition of crop residues and soil organic matter. Conversely, the highest SOC stocks of the 0- to 20-cm soil layer were observed in the NT treatment with the highest N rates, reflecting a greater residue accumulation at the soil Surface. When accounting for the whole soil profile, the variations in surface SOC due to tillage and fertilizer interactions were masked by tillage-induced differences in the 20- to 30-cm soil layer.
  • Authors:
    • Robertson, G. P.
    • Kravchenko, A. N.
    • Basso, B.
    • Senthilkumar, S.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 6
  • Year: 2009
  • Summary: Temporal changes in soil C content vary as a result of complex interactions among different factors including climate, baseline soil C levels, soil texture, and agricultural management practices. The study objectives were: to estimate the changes in soil total C contents that occurred in the past 18 to 21 yr in soils under agricultural management and in never-tilled grassland in southwest Michigan; to explore the relationships between these changes and soil properties, such as baseline C levels and soil texture; and to simulate C changes using a system approach model (SALUS). The data were collected from two long-term experiments established in 1986 and 1988. Georeferenced samples were collected from both experiments before establishment and then were resampled in 2006 and 2007. The studied agricultural treatments included the conventional chisel-plow and no-till management systems with and without N fertilization and the organic chisel-plow management with cover crops. Total C was either lost in the conventional chisel-plowed systems or was only maintained at the 1980s levels by the conservation management systems. The largest loss in the agricultural treatments was 4.5 Mg ha(-1) total C observed in the chisel-plow system without N fertilization. A loss of 17.3 Mg ha(-1) occurred in the virgin grassland sod. Changes in C content tended to be negatively related to baseline C levels. Under no-till, changes in C were positively related to silt + clay contents. The SALUS predictions of soil C changes were in excellent agreement with the observed data for most of the agricultural treatments and for the virgin soil.