• Authors:
    • Karkee, M.
    • McNaull, R. P.
    • Birrell, S. J.
    • Steward, B. L.
  • Source: Transactions of the ASABE
  • Volume: 55
  • Issue: 1
  • Year: 2012
  • Summary: As the demand for biomass feedstocks grows, it is likely that agricultural residue will be removed in a way that compromises soil sustainability due to increased soil erosion, depletion of organic matter, and deterioration of soil physical characteristics. Since soil erosion from agricultural fields depends on several factors including soil type, field terrain, and cropping practices, the amount of biomass that can be removed while maintaining soil tilth varies substantially over space and time. The RUSLE2 soil erosion model, which takes into account these spatio-temporal variations, was used to estimate tolerable agricultural biomass removal rates at field scales for a single-pass crop grain and biomass harvesting system. Soil type, field topography, climate data, management practices, and conservation practices were stored in individual databases on a state or county basis. Geographic position of the field was used as a spatial key to access the databases to select site-specific information such as soil, topography, and management related parameters. These parameters along with actual grain yield were provided as inputs to the RUSLE2 model to calculate yearly soil loss per unit area of the field. An iterative technique was then used to determine site-specific tolerable biomass removal rates that keep the soil loss below the soil loss thresholds (T) of the field. The tolerable removal rates varied substantially with field terrain, crop management practices, and soil type. At a location in a field in Winnebago county, Iowa, with ~1% slope and conventional tillage practices, up to 98% of the 11 Mg ha -1 total above-ground biomass was available for collection with negligible soil loss. There was no biomass available to remove with conventional tillage practices on steep slopes, as in a field in Crawford county, Iowa, with a 12.6% slope. If no-till crop practices were adopted, up to 70% of the total above-ground biomass could be collected at the same location with 12.6% slope. In the case of a soybean-corn rotation with no-till practices, about 98% of total biomass was available for removal at the locations in the Winnebago field with low slopes, whereas 77% of total biomass was available at a location in the Crawford field with a 7.5% slope. Tolerable removal rates varied substantially over an agricultural field, which showed the importance of site-specific removal rate estimation. These removal rates can be useful in developing recommended rates for producers to use during a single-pass crop grain and biomass harvesting operation. However, this study only considered the soil erosion tolerance level in estimating biomass removal rates. Before providing the final recommendation to end users, further investigations will be necessary to study the potential effects of continuous biomass removal on organic matter content and other biophysical properties of the soil.
  • Authors:
    • Derpsch, R.
    • Basch, G.
    • Friedrich, T.
    • Kassam, A.
    • Lahmar, R.
    • Mrabet, R.
    • Serraj, R.
    • Gonzalez-Sanchez, E. J.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: The objective of this article is to review: (a) the principles that underpin conservation agriculture (CA) ecologically and operationally; (b) the potential benefits that can be harnessed through CA systems in the dry Mediterranean climate; (c) current status of adoption and spread of CA in the dry Mediterranean climate countries; and (d) opportunities for CA in the Central and West Asia and North Africa (CWANA) region. CA, comprising minimum mechanical soil disturbance and no-tillage seeding, organic mulch cover, and crop diversification is now practised on some 125 million ha, corresponding to about 9% of the global arable cropped land. The area under CA is spread across all continents and many agro-ecologies, including the dry Mediterranean climate. Empirical and scientific evidence is presented to show that significant productivity, economic, social and environmental benefits exist that can be harnessed through the adoption of CA in the dry Mediterranean climates, including those in the CWANA region. The benefits include: higher productivity and income; climate change adaptation and reduced vulnerability to the erratic rainfall distribution; and reduced greenhouse gas emissions. CA is now spread across several Mediterranean climate countries outside the Mediterranean basin particularly in South America, South Africa and Australia. In the CWANA region, CA is perceived to be a powerful tool of sustainable land management but it has not yet taken off in a serious manner except in Kazakhstan. Research on CA in the CWANA region has shown that there are opportunities for CA adoption in rainfed and irrigated farming systems involving arable and perennial crops as well as livestock.
  • Authors:
    • Ahuja, L. R.
    • Saseendran, S. A.
    • Green, T. R.
    • Ma, L. W.
    • Nielsen, D. C.
    • Walthall, C. L.
    • Ko, J. H.
  • Source: Climatic Change
  • Volume: 111
  • Issue: 2
  • Year: 2012
  • Summary: Agricultural systems models are essential tools to assess potential climate change (CC) impacts on crop production and help guide policy decisions. In this study, impacts of projected CC on dryland crop rotations of wheat-fallow (WF), wheat-corn-fallow (WCF), and wheat-corn-millet (WCM) in the U.S. Central Great Plains (Akron, Colorado) were simulated using the CERES V4.0 crop modules in RZWQM2. The CC scenarios for CO 2, temperature and precipitation were based on a synthesis of Intergovernmental Panel on Climate Change (IPCC 2007) projections for Colorado. The CC for years 2025, 2050, 2075, and 2100 (CC projection years) were super-imposed on measured baseline climate data for 15-17 years collected during the long-term WF and WCF (1992-2008), and WCM (1994-2008) experiments at the location to provide inter-annual variability. For all the CC projection years, a decline in simulated wheat yield and an increase in actual transpiration were observed, but compared to the baseline these changes were not significant ( p>0.05) in all cases but one. However, corn and proso millet yields in all rotations and projection years declined significantly ( p<0.05), which resulted in decreased transpiration. Overall, the projected negative effects of rising temperatures on crop production dominated over any positive impacts of atmospheric CO 2 increases in these dryland cropping systems. Simulated adaptation via changes in planting dates did not mitigate the yield losses of the crops significantly. However, the no-tillage maintained higher wheat yields than the conventional tillage in the WF rotation to year 2075. Possible effects of historical CO 2 increases during the past century (from 300 to 380 ppm) on crop yields were also simulated using 96 years of measured climate data (1912-2008) at the location. On average the CO 2 increase enhanced wheat yields by about 30%, and millet yields by about 17%, with no significant changes in corn yields.
  • Authors:
    • Kornecki, T. S.
    • Price, A. J.
    • Arriaga, F. J.
  • Source: HortScience
  • Volume: 47
  • Issue: 2
  • Year: 2012
  • Summary: A field experiment was conducted in Cullman, AL, to evaluate the effects of three different rollers/crimpers on the termination of a rye ( Secale cereale L) winter cover crop, soil moisture, and yield of sweet corn ( Zea mays saccharata L.) in a no-till system. The following roller types were tested: a straight bar roller, a smooth roller with crimper, and a two-stage roller. These rollers were tested at operating speeds of 3.2 km.h -1 and 6.4 km.h -1. The three rollers/crimpers were compared with a smooth drum roller (no crimping bars) plus glyphosate applied at rate 1.0 kg.ha -1 used as a control. Rye termination dates were selected to be 3 weeks before the recommended sweet corn planting date, which is in the beginning of May for this region. Data indicate that at 3 weeks after rolling for all seasons (2006-2008), 100% rye termination was reached with the smooth drum roller and glyphosate. Two weeks after rolling, average rye termination rates by rollers/crimpers alone were 54.6%, 30.0%, and 50.4% in 2006, 2007, and 2008, respectively. Three weeks after rolling, rye termination rates increased only by ~10% compared with 2 weeks after rolling. These termination levels were below the recommended rate of 90% termination necessary for planting a cash crop into the cover residue. Lower rye termination was probably caused by rolling the rye in an early growth stage (flowering stage). The rollers' operating speed did not influence rye termination rates. Similarly, roller type did not affect soil moisture during the first and second week after rolling. Applying glyphosate with rolling did not increase yield of sweet corn in any of the three growing seasons, and in 2006, sweet corn yield was lower compared with the roller alone treatments. These results are important to vegetable organic systems, in which use of herbicides is not allowed. No significant difference in sweet corn yield was found between operating speeds of 3.2 km.h -1 vs. 6.4 km.h -1 and between the assigned treatments in all growing seasons. However, significant differences in sweet corn yield were detected between the years, most likely as a result of different weather patterns. The lowest sweet corn yield of 3513 kg.ha -1 was reported in 2007 as a result of severe drought in spring and summer of 2007. The highest yield of 15,613 kg.ha -1 was recorded in 2006. In 2008, the yield was 10,158 kg.ha -1. Although the different roller designs were not as effective in ending the rye cover crop compared with the glyphosate treatment, sweet corn yields were unaffected. Multiple rolling operations over the same area could be useful if greater rye termination levels are required without the use of a herbicide, but this recommendation should be tested experimentally in more detail.
  • Authors:
    • Karn, J. F.
    • Liebig, M. A.
    • Tanaka, D. L.
    • Kronberg, S. L.
    • Scholljegerdes, E. J.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 2
  • Year: 2012
  • Summary: Integrated crop-livestock systems have been purported to have numerous agronomic and environmental benefits, yet information documenting their long-term impact on the soil resource is lacking. This study sought to quantify the effects of an integrated crop-livestock system on near-surface soil properties in central North Dakota, USA. Soil bulk density, electrical conductivity, soil pH, extractable N and P, potentially mineralizable N, soil organic carbon (SOC) and total nitrogen (TN) were measured 3, 6 and 9 years after treatment establishment to evaluate the effects of residue management (Grazed, Hayed and Control), the frequency of hoof traffic (High traffic, Low traffic and No traffic), season (Fall and Spring) and production system (integrated annual cropping versus perennial grass) on near-surface soil quality. Values for soil properties were incorporated into a soil quality index (SQI) using the Soil Management Assessment Framework to assess overall treatment effects on soil condition. Residue management and frequency of hoof traffic did not affect near-surface soil properties throughout the evaluation period. Aggregated SQI values did not differ between production systems 9 years after treatment establishment (integrated annual cropping=0.91, perennial grass=0.93; P=0.57), implying a near-identical capacity of each system to perform critical soil functions. Results from the study suggest that with careful management, agricultural producers can convert perennial grass pastures to winter-grazed annual cropping systems without adversely affecting near-surface soil quality. However, caution should be exercised in applying results to other regions or management systems. The consistent freeze/thaw and wet/dry cycles typical of the northern Great Plains, coupled with the use of no-till management, modest fertilizer application rates and winter grazing likely played an important role in the outcome of the results.
  • Authors:
    • Luna, J. M.
    • Mitchell, J. P.
    • Shrestha, A.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic farming has been historically dependent on conventional tillage operations to convert perennial pasture leys to annual crop rotations, incorporate crop residues, compost and cover crops, as well as to mechanically kill existing vegetation. Conventional tillage, however, has long been known to lead to soil degradation and erosion. A recently developed no-till organic production system that uses a roller-crimper technology to mechanically kill cover crops was evaluated in two states in the western United States. In Washington, pumpkins ( Cucurbita spp.) grown in a no-till roller-crimper (NT-RC) system produced yields 80% of conventional tillage, but with fewer weeds. However, in California on-farm research trials in organic cotton ( Gossypium barbadense L.), tomato ( Lycopersicon esculentum Mill.), eggplant ( Solanum melongena L.) and cowpea ( Vigna unguiculata (L.) Walp.), the no-till system produced virtual crop failure, or yields less than 20% of the standard production method. The major problems associated with rolled cover crops in California included reduced crop seedling emergence, planter impediment with excessive residue, lack of moisture and delay in transplanting of vegetable crops due to continued growth of cover crops, in-season crop competition from cover crop regrowth and impracticability of using cultivators. Further, excessive dry residue during summer in California can present the risk of fire. In both California and Oregon, considerable success has been demonstrated with zone tillage (strip tillage) in conventionally produced field and vegetable crops. In a replicated Oregon trial, the organic strip tillage treatment produced 85% of the broccoli ( Brassica oleracea L.) yield compared to a conventional tillage treatment. Our studies suggest that the zone tillage concept may offer opportunities to overcome many of the agronomic challenges facing no-till.
  • Authors:
    • Mailapalli, D. R.
    • Horwath, W. R.
    • Wallender, W. W.
    • Burger, M.
  • Source: Journal of Irrigation and Drainage Engineering
  • Volume: 138
  • Issue: 1
  • Year: 2012
  • Summary: Development of best management practices (BMPs) such as conservation tillage and winter cover crop to mitigate runoff and reduce dissolved chemicals in irrigation runoff is an important objective for controlling surface water pollution attributable to agricultural activities. In this study, the effect of standard tillage (ST), ST with winter cover cropping (STCC), and no-till (NT) management practices on infiltration, runoff, and dissolved organic carbon (DOC) export from furrow-irrigated fields of 244-m length was investigated for summer 2007 and 2008 irrigations. The practices were implemented for 2 years. The average surface residue cover was 11, 44, and 32% for ST, STCC, and NT, respectively, for 2007 and 11, 59, and 61%, respectively, in the following year of the study. Two irrigations in each year were considered for the analysis. The runoff samples were collected from each tillage treatment using ISCO autosamplers at regular time intervals. The infiltration and runoff were estimated using a volume balance model (VBM) by considering a 0.2-m irrigation requirement. Converting from ST to STCC increased the infiltration by 14 and 43% and reduced the runoff by 48 and 43% in 2007 and 2008 irrigations, respectively; whereas, converting ST to NT enhanced the infiltration by 4% in both years and decreased the runoff by 19 and 23% in 2007 and 2008 irrigations, respectively. The authors observed only slightly higher DOC concentrations in STCC, but there was a 24% increase for NT in 2007 irrigations, and both compared to with ST ranged from 3.98 to 5.46 mg/L. The DOC concentration was not significantly different among the treatments in 2008 irrigations (3.48 to 4.6 mg/L). Combining the runoff and DOC concentration effects, the DOC export for STCC was decreased by 55% in both years; whereas, it was decreased by 4 and 27% for NT in 2007 and 2008 irrigations, respectively, compared with ST. Although STCC and NT have higher concentrations, the reduction in export in these treatments is attributable to lower runoff. These results suggest that DOC export can be controlled with STCC practice. No-till showed the same trend, although these results must be confirmed after extended implementation of this practice.
  • Authors:
    • Mehta, V. M.
    • Rosenberg, N. J.
    • Mendoza, K.
  • Source: Agricultural and Forest Meteorology
  • Volume: 152
  • Issue: 1
  • Year: 2012
  • Summary: The Missouri River Basin (MRB) is the largest river basin in the U.S. and is one of the most important crop and livestock-producing regions in the world. In a previous study of associations between decadal climate variability (DCV) phenomena and hydro-meteorological (HM) variability in the MRB for the March-August period, and their impacts on stream flow in the MRB, it was found that positive and negative phases of the Pacific Decadal Oscillation (PDO), the tropical Atlantic sea-surface temperature gradient variability (TAG), and the west Pacific Warm Pool (WPWP) temperature variability were significantly associated with decadal variability in precipitation and surface air temperature in the MRB, with combinations of various phases of these DCV phenomena associated with dry, wet, or neutral HM conditions. It was also found that these DCV phenomena impact stream flow in the MRB substantially via their association with MRB hydro-meteorology. In the present study, the Erosion Productivity Impact Calculator model, also known as the Environmental Policy Integrated Climate (EPIC) model, calibrated and validated for the MRB, was used to simulate yields of dryland corn ( Zea mays L.) and spring and winter wheat ( Triticum aestivum L.), in response to HM anomalies associated with the three DCV phenomena. Realistic values of indices of the three DCV phenomena have major impacts on crop yields, as much as 40-50% of average yield in some locations in the MRB and also evident in MRB-aggregated crop yields; however, our results show that the impacts can be location-specific. Since each of the three DCV phenomena can persist in one phase or another for several years to a decade or longer, and since the simultaneous correlation among these phenomena is negligibly small, their combined and cumulative positive/negative effects on the MRB HM and agricultural production can be dramatic in this major American and global "bread basket". In addition, EPIC's success in simulating long-term crop yields in the MRB, taking technology trends into account, suggests that, if the evolution of major DCV phenomena can be forecast, it may be possible to forecast, as well, some multiyear to decadal measure of crop yields in the MRB with some skill.
  • Authors:
    • Anderson, R. L.
    • Liebig, M. A.
    • Krupinsky, J. M.
    • Hanson, J. D.
    • Tanaka, D. L.
    • Merrill, S. D.
  • Source: Agricultural Systems
  • Volume: 107
  • Year: 2012
  • Summary: The dynamic cropping systems concept proposes a long-term strategy of crop sequencing to achieve production, economic and soil care goals through sound ecological management. This requires that agriculturalists have comprehensive information about how crop species affect following years' crops. Little research exists about how differences in soil type and properties change crop sequence effects. Sandy loam, alluvial-derived soil in south central North Dakota, USA (400 mm/yr precipitation) was the site of a crop sequence experiment in which four species - maize ( Zea mays L.), dry pea ( Pisum sativum L.), spring wheat ( Triticum aestivum L.), and soybean ( Glycine max (L.) Merr.) - were grown in strips one year and in perpendicular strips the following, with spring wheat planted a third year. No-till management was used with three replications in land and two in time. Results were compared with those from two 10*10 sequence experiments on silt loam, glacial till-derived soil. Soil water depletion (SWD) and root growth were deeper in sandy loam soil than in silt loam. During a year of above average precipitation, prior year soybean enhanced spring wheat yield on sandy loam soil by 14% above average, but prior year spring wheat reduced it by 14%. During a year of deficient precipitation, prior crop effects on spring wheat yield ranked in order of expected springtime soil water storage: dry pea, 11%; spring wheat, 4%; soybean, -5%; maize, -10%. Prior crops' SWD largely determined spring soil water, with maize having greatest depletion. Excluding results from a year of low precipitation, prior crops' effects on spring wheat yield on sandy loam soil were similar to results found at two sequence experiments on silt loam soil: dry pea - generally positive effect (N-production, water conservation); spring wheat - negative (disease); soybean - positive (N-production); maize - generally negative (heavier water use). Same year comparison of three crops (nine sequences) on sandy loam soil vs. silt loam showed average dry pea and spring wheat yields being equivalent ( P<0.10). However, average maize yield was 37% lower on silt loam, with maize-after-maize yielding 54% less. The site with sandy loam land had topsoil with lower soil quality indicators (organic C, water holding capacity) than silt loam. However, no-till management and previous grass rendered productivity of the soils equivalent, and superior capacity of the sandy loam site subsoil to conduct water and be conducive to root growth lessened negative, water-generated crop sequence effects.
  • Authors:
    • Weber, D.
    • Way, T. R.
    • Camargo, G. G.
    • Mirsky, S. B.
    • Ryan, M. R.
    • Curran, W. S.
    • Teasdale, J. R.
    • Maul, J.
    • Moyer, J.
    • Grantham, A. M.
    • Spargo, J. T.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic producers in the mid-Atlantic region of the USA are interested in reducing tillage, labor and time requirements for grain production. Cover crop-based, organic rotational no-till grain production is one approach to accomplish these goals. This approach is becoming more viable with advancements in a system for planting crops into cover crop residue flattened by a roller-crimper. However, inability to consistently control weeds, particularly perennial weeds, is a major constraint. Cover crop biomass can be increased by manipulating seeding rate, timing of planting and fertility to achieve levels (>8000 kg ha -1) necessary for suppressing summer annual weeds. However, while cover crops are multi-functional tools, when enhancing performance for a given function there are trade-off with other functions. While cover crop management is required for optimal system performance, integration into a crop rotation becomes a critical challenge to the overall success of the production system. Further, high levels of cover crop biomass can constrain crop establishment by reducing optimal seed placement, creating suitable habitat for seed- and seedling-feeding herbivores, and impeding placement of supplemental fertilizers. Multi-institutional and -disciplinary teams have been working in the mid-Atlantic region to address system constraints and management trade-off challenges. Here, we report on past and current research on cover crop-based organic rotational no-till grain production conducted in the mid-Atlantic region.