• Authors:
    • Paustian, K.
    • Ogle, S.
    • Lee, J.
    • De Gryze, S.
    • Six, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 144
  • Issue: 1
  • Year: 2011
  • Summary: We predicted changes in yields and direct net soil greenhouse gas (GHG) fluxes from converting conventional to alternative management practices across one of the world's most productive agricultural regions, the Central Valley of California, using the DAYCENT model. Alternative practices included conservation tillage, winter cover cropping, manure application, a 25% reduction in N fertilizer input and combinations of these. Alternative practices were evaluated for all unique combinations of crop rotation, climate, and soil types for the period 1997-2006. The crops included were alfalfa, corn, cotton, melon, safflower, sunflower, tomato, and wheat. Our predictions indicate that, adopting alternative management practices would decrease yields up to 5%. Changes in modeled SOC and net soil GHG fluxes corresponded to values reported in the literature. Average potential reductions of net soil GHG fluxes with alternative practices ranged from -0.7 to -3.3 Mg CO(2)-eq ha(-1) yr(-1) in the Sacramento Valley and -0.5 to -2.5 Mg CO(2)-eq ha(-1) yr(-1) for the San Joaquin Valley. While adopting a single alternative practice led to modest net soil GHG flux reductions (on average -1 Mg CO(2)-eq ha(-1) yr(-1)), combining two or more of these practices led to greater decreases in net soil GHG fluxes of up to -3 Mg CO(2)-eq ha(-1) yr(-1). At the regional scale, the combination of winter cover cropping with manure application was particularly efficient in reducing GHG emissions. However, GHG mitigation potentials were mostly non-permanent because 60-80% of the decreases in net soil GHG fluxes were attributed to increases in SOC, except for the reduced fertilizer input practice, where reductions were mainly attributed to decreased N(2)O emissions. In conclusion, there are long-term GHG mitigation potentials within agriculture, but spatial and temporal aggregation will be necessary to reduce uncertainties around GHG emission reductions and the delivery risk of the associated C credits. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Leifert, C.
    • Critchley, C. N. R.
    • Eyre, M. D.
    • Wilcockson, S. J.
  • Source: European Journal of Agronomy
  • Volume: 34
  • Issue: 3
  • Year: 2011
  • Summary: A survey of 128 plots, in 2008, of a trial where the effects of crop protection can be separated from those of fertility management, generated weed cover data within six crops (winter wheat, winter barley, spring barley, potatoes, cabbages and a grass/clover ley). The effects of the 2008 crop types, of the two preceding crops and of organic and conventional crop protection and fertility management, were assessed using mixed-effects models and constrained ordination. Cover data for 22 weed species and for monocotyledon, dicotyledon, annual, perennial and total weed cover were used. Cover of 15 weed species, and of the five weed groups, was significantly affected by 2008 crops, with cover highest in spring beans and cabbage. Nine and four weed species 2008 cover were significantly related to crops grown in 2007 and 2006 respectively, as were dicotyledon, annual and total weed cover, but not monocotyledon or perennial cover. Cover of 15 species, and the five groups, was significantly higher in plots with organic crop protection, but only eight species and annuals were significantly affected by fertility management. Crop:crop protection produced the most significant interactions with most cover in organically managed plots. Five species, perennials and total weed cover produced significant three-factor models. The greatest weed cover was in organic crop protected but conventionally fertilised spring barley and the least in totally conventional winter barley. Other factors such as crop density and mechanical weeding also affected 2008 weed cover. The ordination indicated that most of the 22 species were strongly associated with crops from all three years. The sequence of crops in the rotation had a profound effect on weed cover. Where three spring-sown, difficult to weed, crops were grown in sequence (spring beans, potatoes and vegetables, spring barley) weed cover increased. However, cover was limited in grass/clover and some cereal plots with different preceding crops. Models predicting weed cover may need to take into account crop sequences within crop rotations, as well as the more usual management inputs. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Kumar, V.
    • Kumar, V.
    • Saharawat, Y. S.
    • Ladha, J. K.
    • Gathala, M. K.
    • Sharma, P. K.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 5
  • Year: 2011
  • Summary: Rice-wheat (Oryza sativa L.-Triticum aestivum L.) rotation is the major production system in Asia, covering about 18 million ha. Conventional practice of growing rice (puddled transplanting) and wheat (conventional till, CT) deteriorate soil physical properties, and are input- and energy-intensive. Zero-tillage (ZT) along with drill-seeding have been promoted to overcome these problems. A 7-yr permanent plot study evaluated various tillage and crop establishment (CE) methods on soil physical properties with an aim to improve soil health and resource-use efficiency. Treatments included transplanting and direct-seeding of rice on flat and raised beds with or without tillage followed by wheat in CT and ZT soil. Bulk density (D(b)) of the 10- to 20-cm soil layer was highest under puddled treatments (1.74-1.77 Mg m(-3)) and lowest under ZT treatments (1.66-1.71 Mg m(-3)). Likewise, soil penetration resistance (SPR) was highest at the 20-cm depth in puddled treatments (3.46-3.72 MPa) and lowest in ZT treatments (2.51-2.82 MPa). Compared with conventional practice, on average, water-stable aggregates (WSAs) > 0.25 mm were 28% higher in ZT direct-seeding with positive time trend of 4.02% yr(-1). Infiltration was higher (0.29-0.40 cm h(-1)) in ZT treatments than puddled treatments (0.18 cm h(-1)). The least-limiting water range was about double in ZT direct-seeding than that of conventional practice. Gradual improvement in soil physical parameters in ZT system resulted in improvement in wheat yield and is expected to be superior in long-run on system (rice+wheat) basis. Further research is needed to understand mechanisms and requirements of two cereals with contrasting edaphic requirements in their new environment of ZT direct-seeding.
  • Authors:
    • Burr, C.
    • Thorburn, J.
    • Irmak, S.
    • Yang, H. S.
    • Grassini, P.
    • Cassman, K. G.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 1
  • Year: 2011
  • Summary: Appropriate benchmarks for water productivity (WP), defined here as the amount of grain yield produced per unit of water supply, are needed to help identify and diagnose inefficiencies in crop production and water management in irrigated systems. Such analysis is lacking for maize in the Western U.S. Corn Belt where irrigated production represents 58% of total maize output. The objective of this paper was to quantify WP and identify opportunities to increase it in irrigated maize systems of central Nebraska. In the present study, a benchmark for maize WP was (i) developed from relationships between simulated yield and seasonal water supply (stored soil water and sowing-to-maturity rainfall plus irrigation) documented in a previous study; (ii) validated against actual data from crops grown with good management over a wide range of environments and water supply regimes ( n=123); and (iii) used to evaluate WP of farmer's fields in central Nebraska using a 3-y database (2005-2007) that included field-specific values for yield and applied irrigation ( n=777). The database was also used to quantify applied irrigation, irrigation water-use efficiency (IWUE; amount of yield produced per unit of applied irrigation), and the impact of agronomic practices on both parameters. Opportunities to improve irrigation management were evaluated using a maize simulation model in combination with actual weather records and detailed data on soil properties and crop management collected from a subset of fields ( n=123). The linear function derived from the relationship between simulated grain yield and seasonal water supply, namely the mean WP function (slope=19.3 kg ha -1 mm -1; x-intercept=100 mm), proved to be a robust benchmark for maize WP when compared with actual yield and water supply data. Average farmer's WP in central Nebraska was ~73% of the WP derived from the slope of the mean WP function. A substantial number of fields (55% of total) had water supply in excess of that required to achieve yield potential (900 mm). Pivot irrigation (instead of surface irrigation) and conservation tillage in fields under soybean-maize rotation had the greatest IWUE and yield. Applied irrigation was 41 and 20% less under pivot and conservation tillage than under surface irrigation and conventional tillage, respectively. Simulation analysis showed that up to 32% of the annual water volume allocated to irrigated maize in the region could be saved with little yield penalty, by switching current surface systems to pivot, improving irrigation schedules to be more synchronous with crop water requirements and, as a fine-tune option, adopting limited irrigation.
  • Authors:
    • Blaise, D.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 2
  • Year: 2011
  • Summary: Transgenic Bt cotton hybrids, in India, now constitute more than 90% of the cotton area. Conservation tillage systems such as reduced tillage (RT) improve soil health and crop productivity. Field experiments were conducted to study the response of Bt cotton hybrids to the tillage methods in a split plot design for three years (2005-2006 to 2007-2008) with tillage practices as main plots (conventional tillage {CT}, RT with two inter-row cultivations {RT(1)} and RT with no inter-row cultivation {RT(2)}). In the sub-plot, in situ green manure (GM) was included along with 100 (GM + N(100)), 80 (GM + N(80)) and 60 kg N ha(-1) (GM + N(60)) and were compared to N alone (N(100)). Growth, yield and fibre quality of Bt transgenic cotton hybrid (RCH-2 Bt) were monitored during the study. In all seasons, weed density and biomass were significantly lower in the RT treatments than in the CT treatments. Taller plants with more main stem nodes were produced on the RT plots (63.6-75.8 cm) than on the CT plots (58.1-70.2 cm). Thus, plants of RT treatment retained more bolls (60.8-62.0 m(-2)) than those of the CT treatment (52.4 m(-2)). Averaged over seasons, RT treatment had seed cotton yield (1717-1740 kg ha(-1)) significantly higher than the CT treatment (1489 kg ha(-1)). The treatments N(100), GM + N(100) and GM + N(80) (1687-1734 kg ha(-1)) did not differ and were significantly better than the GM + N(60) (1303 kg ha(-1)). Tillage x GM interaction was significant in two of three years and data combined over years. The RT plots with GM had significantly greater yield than the CT plots. Compared to the CT treatment, the RT plots had significantly greater proportion of water stable aggregates (48.6% vs. 54.4-56.0%) and mean weight diameter (0.47 mm vs. 0.49-0.51 mm). The GM plots had significantly higher WSA and MWD than those without. Further, soil moisture content was greater in the GM mulched plots up to 0.60 m depth compared to without GM treatment (CT + N(100)). Favourable soil physical properties may have contributed to improved seed cotton yield in the RT treatments with GM than in the CT treatment. Fibre quality was not affected by either the tillage systems or GM. This study indicates that Bt transgenic cotton can be grown under RT systems with an in situ legume GM. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Lecler, N. L.
    • Tweddle, P. B.
  • Source: Proceedings of the Annual Congress - South African Sugar Technologists' Association
  • Issue: 83
  • Year: 2010
  • Summary: Many guidelines and recommendations for sugarcane farming are aimed at achieving a large number of ratoon crops. One of the reasons for this is that the replanting costs can be considerable when a field is conventionally tilled and replanted. Thus, delaying reestablishment makes financial sense provided the cost savings are greater than any yield and revenue penalties. An alternative is to introduce a controlled traffic and zero-till farming system (CTF), thereby lowering re-establishment costs and potentially allowing for fewer ratoon crops and more frequent green manure or break crops. A rigorous yield, sucrose content, costing and cash-flow analysis, based on published research findings and detailed costing of representative machinery, showed that a CTF system with only three ratoon crops was far more profitable than a conventional farming system involving eight ratoon crops and more intensive tillage operations. A doubling in profitability was shown when the yield benefits reported with break crops and the yield decline rates reported under conventional farming systems were included in the analysis. Substantial gains in water use productivity were also shown, up to nearly 80% improvement over a conventional farming system. Adoption of a CTF system with only three ratoon crops is therefore highly recommended and should be taken very seriously by decision-makers in the sugarcane industry.
  • Authors:
    • Lindau, C.
    • Bollich, P.
    • Bond, J.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 41
  • Issue: 13
  • Year: 2010
  • Summary: This field study was conducted over a 3-year time period in Louisiana to determine which soybean ( Glycine max L.) tillage practice discharged the least amount of nutrients and sediment from experimental plots after rainfall/runoff events. In addition, tillage effect on soybean yield was investigated. Experimental design consisted of three Louisiana soybean tillage treatments [conventional (CT), stale seedbed (SS), and no-till (NT)] with three replications per treatment. A randomized complete-block design was used for statistical analysis. Each of the nine treatment plots measured 27.1 m by 106.4 m and was equipped with an automatic runoff sampler integrated with a continuously recording flow meter and H-flume. Composite runoff samples were analyzed for ammonium N (NH 4+-N), nitrate N (NO 3--N), total Kjeldahl nitrogen (TKN), total phosphorus (TP), orthophosphorus (ortho-P), total organic carbon (TOC), and total solids (TS). Analyte discharge (kg ha -1) per rainfall/runoff event was calculated using runoff concentrations and total runoff flows (L). Statistical analysis showed that discharge treatment means were highly variable and that tillage practice had little or no effect on total runoff and on the amount of N and P discharged from treatment plots. Treatment differences over the study were nonsignificant for all N and P forms 93% and 61% of the time, respectively. Only 21% of the time was mean treatment total runoff significant ( P≤0.05). Stale seedbed and NT practices reduced sediment discharges over segments of the soybean growing seasons. Total organic carbon discharge from the NT plots was significantly greater 42% of the time. Soybean yields were highly variable within and between treatments and strongly influenced by rainfall, disease, and insects.
  • Authors:
    • Mulvaney, M. J.
    • Wood, C. W.
    • Kemble, J. M.
    • Balkcom, K. S.
    • Shannon, D. A.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 5
  • Year: 2010
  • Summary: A combination of high biomass cover crops with organic mulches may be an option for no-till vegetable production, but information on mineralization rates from these residues is lacking. The objective of this study was to assess nutrient release rates and persistence from mimosa ( Albizia julibrissin Durazz.), lespedeza [ Lespedeza cuneata (Dum. Cours.) G. Don], oat ( Avena sativa L.) straw, and soybean [ Glycine max (L.) Merr.] residues under conventional and conservation tillage. The experiment was conducted in Tallassee, AL using litterbag methodology in a split-plot design (main plots: two tillage systems; subplots: four residue types). Comparison of rate constants showed that labile portions of residues was more affected by tillage than recalcitrant portions. In spring, mimosa residue contained 78 kg N ha -1 when buried the previous fall, compared to 123 kg N ha -1 when surface placed; soybean residue showed similar results (39 vs. 72 kg N ha -1, respectively). Results were similar for lespedeza (72 vs. 101 kg N ha -1, respectively), but not for oat straw (24 vs. 26 kg N ha -1, respectively). After 1 yr, surface placed mimosa residue mineralized 33% of initial N compared to 71% when buried, while surface placed lespedeza mineralized 36% of initial N compared to 64% when buried. Soybean residue mineralized N quickly regardless of placement (73 vs. 87%, respectively). This study demonstrates that cut-and-carry mulches may be used under conservation tillage for the enhancement of soil organic matter (SOM), soil organic carbon (SOC), and soil N status.
  • Authors:
    • Tomar, S. S.
    • Yadav, A. K.
    • Singh, A.
    • Pal, G.
    • Shahi, U. P.
    • Kumar, A.
    • Singh, B.
    • Gupta, R. K.
    • Naresh, R. K.
  • Source: Progressive Agriculture
  • Volume: 10
  • Issue: 2
  • Year: 2010
  • Summary: Resource conserving technologies (RCTs) with double no-till practices represents a major shift in production techniques for attaining optimal productivity, profitability and water use in rice-wheat system in Indo-Gangetic plains. Conventional tillage and crop establishment methods such as puddled transplanting in the ricewheat ( Oryza sativa L.- Triticum aestivum L.) system in the Indo-Gangetic Plains (IGP) require a large amount of water and labor, both of which are increasingly becoming scarce and expensive. We attempted to evaluate alternatives that would require smaller amounts of these two inputs. A field experiment was conducted in the Western IGP for 2 years to evaluate various tillage and crop establishment systems for their efficiency in labor, water, and energy use and economic profitability. The soil physical properties (bulk density, mean weight diameter of aggregates and infiltration rate) improved significantly compared to puddled transplanted rice-conventional till wheat system. The wide beds and double no-till with flat layouts in rice-wheat system is under evaluation in different scenario of soil, climate, crop cultivars and seeding/crop establishment techniques (direct seeding, transplanting) and showed non consistent results. Systematic information on various aspects of narrow/wide beds is lacking. The productivity of rice with wide beds was at par compared to reduced tillage transplanted rice layouts but, the wheat productivity was reverse as it was highest under wide beds. The RW system productivity was highest with wide raised beds does differ significantly with other tillage and crop establishment techniques except with mulch crop establishment techniques. The water productivity of both rice and wheat was markedly improved with wide beds compared to other tillage and crop establishment techniques. Under research managed trials (rice on double no-till flat) with basmati rice, the profitability was maximum with ZTDSR (US $ 505 ha -1) and was least with direct seeded on narrow raised beds (US$305 ha -1). The study showed that the conventional practice of puddled transplanting could be replaced with no-tillage-based crop establishment methods to save water and labor. However, the occurrence and distribution of rainfall during the cropping season had considerable influence on the savings in irrigation water.
  • Authors:
    • Silva, J. R. M. da
    • Silva, L. L.
    • Pisco, A. M. V.
    • Torres, C. J. V.
  • Source: International Conference on Agricultural Engineering
  • Year: 2010
  • Summary: Centre-pivot irrigation systems frequently cause surface runoff and erosion problems. This is more evident in complex topographies and low infiltrability soils. To overcome these problems farmers have tried different tillage systems, attaining different results, depending on soil type and irrigation management. Field tests, using small plots, were carried out in a Mediterranean soil with three different tillage systems: no-till, basin tillage and conventional tillage, as a control practice. Conventional tillage showed the highest runoff values (30% of collected water depth) with significant differences to no-till (15%) and basin tillage (2%). Maximum average values of sediment yields per irrigation event were lower for basin tillage (4.46 kg/ha) and no-till (9.59 kg/ha) compared to conventional tillage (23.45 kg/ha). The no-till system showed higher soil water content along all the irrigation season compared to the other two tillage systems. From a soil and water conservation point of view the basin tillage practice is the best option. But, from an economic point of view the no-till practice can be also a good option in these conditions.