Impact of Cover Crops and Nitrogen Application on Nitrous Oxide Fluxes and Grain Yield of Sorghum and Maize PDF Download
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Author: George Yakubu Mahama
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Languages : en
Pages :
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Leguminous cover crops systems have been envisaged as a critical component of sustainable agriculture due to their potential to increase soil productivity through cycling of carbon (C) and nitrogen (N) in agricultural systems. The objectives of this study were to evaluate the performance of leguminous summer cover crops; cowpea [Vigna unguiculata (L.) Walp.], pigeon pea [Cajanus cajan (L.) Millsp], sunn hemp (Crotalaria juncea L.) and double-cropped grain crops; grain sorghum [Sorghum bicolor (L.) Moench] and soybean [Glycine max (L.) Merr.] after winter wheat (Triticum aestivum L.) and to determine the effects of these crops and varying N rates in the cropping system on nitrous oxide (N2O) emissions, growth and yield of succeeding grain sorghum and maize (Zea mays L.) crop, soil aggregation, aggregate-associated C, and N. Field and laboratory studies were conducted for two years. The cover crops and double-cropped grain crops were planted immediately after winter wheat harvest. The cover crops were terminated at the beginning of flowering. Nitrogen fertilizer (urea 46% N) rates of 0, 45, 90, 135, and 180 kg N ha−1 were applied to grain sorghum or maize in fallow plots. Pigeon pea and grain sorghum had more C accumulation than cowpea, sunn hemp and double-cropped soybean. Pigeon pea and cowpea had more N uptake than sunn hemp and the double-cropped grain crops. Fallow with N fertilizer application produced significantly greater N2O emissions than all the cover crops systems. Nitrous oxide emissions were relatively similar in the various cover crop systems and fallow with 0 kg N ha−1. Grain yield of sorghum and maize in all the cover crop and double cropped soybean systems was similar to that in the fallow with 45 kg N ha−1. Both grain sorghum and maize in the double-cropped soybean system and fallow with 90 kg N ha−1 or 135 kg N ha−1 gave profitable economic net returns over the years. The double-cropped grain sorghum system increased aggregate-associated C and whole soil total C, and all the cover crop and the double-cropped soybean systems increased aggregate-associated N and soil N pools. Inclusion of leguminous cover crops without N fertilizer application reduced N2O emissions and provided additional C accumulation and N uptake, contributing to increased grain yield of the following cereal grain crop.
Author: George Yakubu Mahama
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Leguminous cover crops systems have been envisaged as a critical component of sustainable agriculture due to their potential to increase soil productivity through cycling of carbon (C) and nitrogen (N) in agricultural systems. The objectives of this study were to evaluate the performance of leguminous summer cover crops; cowpea [Vigna unguiculata (L.) Walp.], pigeon pea [Cajanus cajan (L.) Millsp], sunn hemp (Crotalaria juncea L.) and double-cropped grain crops; grain sorghum [Sorghum bicolor (L.) Moench] and soybean [Glycine max (L.) Merr.] after winter wheat (Triticum aestivum L.) and to determine the effects of these crops and varying N rates in the cropping system on nitrous oxide (N2O) emissions, growth and yield of succeeding grain sorghum and maize (Zea mays L.) crop, soil aggregation, aggregate-associated C, and N. Field and laboratory studies were conducted for two years. The cover crops and double-cropped grain crops were planted immediately after winter wheat harvest. The cover crops were terminated at the beginning of flowering. Nitrogen fertilizer (urea 46% N) rates of 0, 45, 90, 135, and 180 kg N ha−1 were applied to grain sorghum or maize in fallow plots. Pigeon pea and grain sorghum had more C accumulation than cowpea, sunn hemp and double-cropped soybean. Pigeon pea and cowpea had more N uptake than sunn hemp and the double-cropped grain crops. Fallow with N fertilizer application produced significantly greater N2O emissions than all the cover crops systems. Nitrous oxide emissions were relatively similar in the various cover crop systems and fallow with 0 kg N ha−1. Grain yield of sorghum and maize in all the cover crop and double cropped soybean systems was similar to that in the fallow with 45 kg N ha−1. Both grain sorghum and maize in the double-cropped soybean system and fallow with 90 kg N ha−1 or 135 kg N ha−1 gave profitable economic net returns over the years. The double-cropped grain sorghum system increased aggregate-associated C and whole soil total C, and all the cover crop and the double-cropped soybean systems increased aggregate-associated N and soil N pools. Inclusion of leguminous cover crops without N fertilizer application reduced N2O emissions and provided additional C accumulation and N uptake, contributing to increased grain yield of the following cereal grain crop.
Author: Giovani Preza Fontes
Publisher:
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Languages : en
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Growing cover crops (CCs) in rotation with cash crops has become popular in recent years for their many agroecosystem benefits, such as influencing nutrient cycling and reducing nutrient losses. This study aimed to (i) determine the long-term effects of no-till with CCs and varying nitrogen (N) rates on subsequent sorghum [Sorghum bicolor (L.) Moench] yield and yield components, (ii) assess how CCs affect the N dynamic in the soil-crop relationship during the growing season and N use efficiency (NUE) of sorghum, and (iii) define and evaluate important periods of nitrous oxide (N2O) losses throughout the cropping system. Field experiments were conducted during the 2014-15 and 2015-16 growing season in a three-year no-till winter wheat (Triticum aestivum L.) -- sorghum -- soybean [Glycine max (L.) Merr] rotation. Fallow management consisted of a chemical fallow (CF) control plus four CCs and a double-crop soybean (DSB) grown after wheat harvest. Nitrogen fertilizer was subsurface banded at five rates (0, 45, 90, 135, and 180 kg ha−1) after sorghum planting. On average, DSB and late-maturing soybean (LMS) provided one-third and one-half of the N required for optimum economic grain yield (90 kg N ha−1), respectively; resulting in increased grain yield when compared to the other CCs and CF with 0-N application. Crimson clover (Trifolium incarnatum L.) and daikon radish (Raphanus sativus L.) had no or negative effects on sorghum yield and N uptake relative to CF across all N rates. Sorghum-sudangrass (SS) (Sorghum bicolor var. sudanese) significantly reduced N uptake and grain yield, even at higher N rates. Sorghum following CF had the lowest NUE at optimum grain yield when compared to all CC treatments, suggesting that CCs have a tendency to improve NUE. Cover crops reduced N2O emissions by 65% during the fallow period when compared to CF; however, DSB and SS increased emissions when N was applied during the sorghum phase, indicating that N fertilization might be the overriding factor. Moreover, about 50% of the total N2O emissions occurred within 3 weeks after N application, regardless of the cover crop treatment, indicating the importance of implementing N management strategies to reduce N2O emissions early in the growing season. Overall, these results show that CC selection and N fertilizer management can have significant impacts on sorghum productivity and N2O emissions in no-till cropping systems.
Author: Matthew Nielsen
Publisher:
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Category :
Languages : en
Pages :
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Cover crops (CCs) are included in rotations between cash crops for many reasons, including reducing erosion, compaction, and sequestering nutrients for optimal crop performance. The objectives of this study were to i) determine the effects of increasing cropping system intensity on CC biomass accumulation, C:N ratio, and residual inorganic profile nitrogen and ii) determine how intensity effects sorghum (Sorghum bicolor L.) growth, development, and yield in a no-till wheat (Triticum aestivum L.), sorghum, soybean (Glycine max L.) rotation. The experiment was conducted in a randomized complete block design with four treatments: chemical fallow (CF), double-crop soybeans (DSB), double-crop soybeans plus a spring cover crop before sorghum (DSBCC), and a summer cover crop mixture after wheat (CCMIX). Nitrogen (N) rates consisting of 0, 40, 80, 120, and 160 pounds acre−1 were subsurface banded after sorghum planting. Sorghum growth and development were characterized by Canopeo (percent canopy cover) and GreenSeeker (NDVI), from seedling through boot stages, by recording days from planting to half bloom, and by chlorphyll readings (SPAD) at half bloom or early grain fill. Sorghum biomass was sampled after physiological maturity to determine N uptake and yield components. Averaged over three years, summer and fall growth of CCMIX produced the greatest biomass at more than 2,000 pounds acre−1 and had the greatest C:N ratio compared to DSBCC and CCMIX sampled in the spring. Residual inorganic profile N at sorghum planting, when averaged over years, was roughly 26 pounds acre−1 and 13 pounds acre−1 less after DSBCC and CCMIX, respectively compared to after CF and DSB. Including a spring cover crop before sorghum (DSBCC) consistently reduced vegetative growth and development of sorghum.Sorghum growth response to CCMIX was inconsistent depending on year. In 2018, when there was no winter survival of the cover crop, sorghum growth after CCMIX was not different from CF. The CCMIX treatment reduced sorghum SPAD values by 6% and 7% in 2017 and 2019, respectively, and N uptake by 41 and 27 pounds acre−1 in 2017 and 2019, respectively. The spring cover crop immediately before sorghum planting (DSBCC) reduced sorghum biomass by 9% (2017) and 27% (2018) compared to CF, though CF was not different from DSB and CCMIX. In 2019, DSBCC was not different from CF, and sorghum after DSB had 10% greater biomass yield than sorghum after DSBCC. Sorghum grain yield was reduced by more than 50% after DSBCC in 2018 compared to CF, though CF, DSB, and CCMIX were not different. In 2019, sorghum grain yields after CF, DSBCC, and CCMIX were not different, and sorghum after DSB had the greatest yields, 7% more than DSBCC. Including double crop or cover crop in a no-till cropping system slowed early-seasoon growth and development and reduced N uptake of the subsequent sorghum crop but had minimal impact on grain yield with adequate weather conditions. However, a spring-planted CC with substantial biomass accumulation immediately before sorghum planting substantially reduced sorghum yield when spring rainfall was below normal.
Author: Holly S. Weber
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Languages : en
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Nitrogen fertilizers play an essential role in agricultural production in Kansas, particularly in row crops such as corn (Zea mays L.) and grain sorghum (Sorghum bicolor (L.) Moench). A good portion of the corn and grain sorghum grown in Kansas is typically grown using no-till production systems. These systems leave a large amount of surface residue on the soil surface, which can lead to ammonia volatilization losses from surface applied urea-containing fertilizers and immobilization of N fertilizers placed in contact with the residue. Leaching and denitrification can also be a problem on some soils. Current nitrogen prices, as well as concerns over environmental stewardship, are forcing producers to make smarter choices in the fertilizer products used as well as when and how the materials are applied, to optimize their nitrogen use efficiency. A common practice throughout Kansas is to apply N fertilizers prior to planting, sometimes up to 6 month prior to planting. What affect does this practice have on nitrogen availability to the growing crop? Current Kansas State University (KSU) soil test fertilizer recommendations assume 50% nitrogen use efficiency. This means of every pound of nitrogen applied only half will be utilized by the plant and turned into valuable grain. Possible solutions to help increase nitrogen use efficiency are the use of nitrogen additives which are currently on the market and claim to reduce nitrogen loss through denitrification and volatilization as well as the use of timing and application of fertilizers to further increase nitrogen use efficiency. The objective of this study is to evaluate different N fertilizer products, as well as additives and application practices and determine whether specific combinations can improve yield and N use efficiency of no-till corn and grain sorghum. The long-term goal of this study is to quantify some of these relationships to assist farmers in selecting specific combinations that could enhance yield and profitability. In this study five tools for preventing N loss were examined: fertilizer placement, or placing N below the soil surface or in bands on the residue-covered soil surface to reduce immobilization and/or volatilization; use of a urease inhibitor Agrotain (NBPT) that blocks the urease hydrolysis reaction that converts urea to ammonia and potentially could reduce ammonia volatilization; the use of a commercially available additive, Agrotain Plus, that contains both a nitrification inhibitor (DCD) and a urease inhibitor to slow both urea hydrolysis and the rate of ammonium conversion to nitrate and subsequent denitrification or leaching loss; use of a commercial product NutriSphere-N, which claims urease and nitrification inhibition; and the use of a polyurethane plastic-coated urea to delay release of urea fertilizer until the crop can use it. The ultimate goal of using these practices or products is to increase N uptake by the plant and enhance yield. An important measurement that was developed for this research was the use of a greenleaf firing index which used the number of green leaves below the ear at pollination as a key measurement in determining the effectiveness of fertilizer placement, application method, application timing and the use of nitrogen additives. If significant differences in lower leaf nitrogen stress are found, the potential exists to further develop this index and correlate differences observed with key parameters of nitrogen uptake such as ear-leaf nitrogen concentration, total nitrogen uptake and grain yield. Results observed from this research show that the potential to increase nitrogen use efficiency and reduce nitrogen loss do exist with the use of certain nitrogen additives, application methods and application timing. When conditions are conducive for nitrogen loss the use of currently available tools to protect nitrogen from volatilization, immobilization and/or denitrification loss significantly increased yields in the corn experiments. Results from the grain sorghum research indicate that when N losses limit yield, the use of products and practices enhance yield. In locations where nitrogen loss is minimal or low yields limit nitrogen response, the use of these practices was not found to be helpful.
Author: Florian Rodriguez Crespo
Publisher:
ISBN:
Category : Cover crops
Languages : en
Pages : 128
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Author: Shiva Ladan
Publisher:
ISBN:
Category :
Languages : en
Pages : 300
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Nitrous oxide (N2O) is an atmospheric constituent that contributes to climate warming and stratospheric ozone depletion. A large fraction of the anthropogenic N2O emission originates from agricultural soils suggesting therefore a strong connection between N2O accumulation in the atmosphere and agricultural land management. During the last 2-3 decades, no-till (NT) farming and integration of cover crops into crop rotation represent two major developments in agriculture, but much remains to be learned about the impact of these management approaches on N2O emission and underlying biological soil factors. This dissertation focuses on the contribution of different components of the soil microflora to N2O production, and how different types of cover crops (legume vs grass) affect the soil microbial community composition, mineral N availability, and N2O emission in plowed (PT) and NT soils. To address these questions, several laboratory and greenhouse experiments were conducted. Results of these experiments documented soil microbial community responses to cover crop addition and could inform the selection of cover crops most suitable to soils under different tillage practices.
Author:
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Category : Agriculture
Languages : en
Pages : 634
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Author: Lucas P. Gakale
Publisher:
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Category : Crops and nitrogen
Languages : en
Pages : 182
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Author: Mark Liebig
Publisher: Academic Press
ISBN: 012386898X
Category : Technology & Engineering
Languages : en
Pages : 602
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Book Description
Global climate change is a natural process that currently appears to be strongly influenced by human activities, which increase atmospheric concentrations of greenhouse gases (GHG). Agriculture contributes about 20% of the world’s global radiation forcing from carbon dioxide, methane and nitrous oxide, and produces 50% of the methane and 70% of the nitrous oxide of the human-induced emission. Managing Agricultural Greenhouse Gases synthesizes the wealth of information generated from the GRACEnet (Greenhouse gas Reduction through Agricultural Carbon Enhancement network) effort with contributors from a variety of backgrounds, and reports findings with important international applications. Frames responses to challenges associated with climate change within the geographical domain of the U.S., while providing a useful model for researchers in the many parts of the world that possess similar ecoregions Covers not only soil C dynamics but also nitrous oxide and methane flux, filling a void in the existing literature Educates scientists and technical service providers conducting greenhouse gas research, industry, and regulators in their agricultural research by addressing the issues of GHG emissions and ways to reduce these emissions Synthesizes the data from top experts in the world into clear recommendations and expectations for improvements in the agricultural management of global warming potential as an aggregate of GHG emissions
Author: Pedro A. Sanchez
Publisher: Cambridge University Press
ISBN: 1107176050
Category : Business & Economics
Languages : en
Pages : 685
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Book Description
Long-awaited second edition of classic textbook, brought completely up to date, for courses on tropical soils, and reference for scientists and professionals.
