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Cover Crop Biomass Harvest Influences Cotton Nitrogen Utilization and Productivity  [PDF]
F. Ducamp,F. J. Arriaga,K. S. Balkcom,S. A. Prior,E. van Santen,C. C. Mitchell
International Journal of Agronomy , 2012, DOI: 10.1155/2012/420624
Abstract: There is a potential in the southeastern US to harvest winter cover crops from cotton (Gossypium hirsutum L.) fields for biofuels or animal feed use, but this could impact yields and nitrogen (N) fertilizer response. An experiment was established to examine rye (Secale cereale L.) residue management (RM) and N rates on cotton productivity. Three RM treatments (no winter cover crop (NC), residue removed (REM) and residue retained (RET)) and four N rates for cotton were studied. Cotton population, leaf and plant N concentration, cotton biomass and N uptake at first square, and cotton biomass production between first square and cutout were higher for RET, followed by REM and NC. However, leaf N concentration at early bloom and N concentration in the cotton biomass between first square and cutout were higher for NC, followed by REM and RET. Seed cotton yield response to N interacted with year and RM, but yields were greater with RET followed by REM both years. These results indicate that a rye cover crop can be beneficial for cotton, especially during hot and dry years. Long-term studies would be required to completely understand the effect of rye residue harvest on cotton production under conservation tillage. 1. Introduction Nitrogen is the most difficult nutrient to manage when growing cotton. About 5,445,749?ha of the cotton were planted in the USA in 2003 [1]. Applying optimum N rates is necessary to maximize economic yields and minimize the negative impacts that N overapplication can have on the crop and environment [2]. Higher N rates than required can result in excessive vegetative growth which increases the proportion of immature bolls, reduces lint quality and cotton yields, and increases disease and insect damage [3–6]. However, N deficiencies can reduce vegetative and reproductive growth and decrease yields [3]. Many parameters combine to determine the optimum N rates for cotton, such as soil type, location, N application method, tillage system, water availability, use of winter cover crops, and potential yield [7]. Conservation systems for cotton production in the southeastern US have increased in adoption to approximately 50% of the 2.9?million?ha planted in this area [8]. The use of winter cover crops has been well documented as an effective method for improving soil chemical, biological, and physical properties [9, 10]. Among winter crop species, winter cereals like rye can have many benefits because they produce high amounts of biomass, are easy to establish and kill, and provide good ground cover during the winter [8, 11]. However, the
Biomass and Nutrient Accumulation of Cover Crops in the Crop Off-season in Cerrado, in Goiás State, Brazil  [cached]
Leandro Pereira Pacheco,Marinete Martins de Sousa Medeiros,Rodrigo Fonseca da Silva,Leandro dos Santos Soares
Journal of Agricultural Science , 2012, DOI: 10.5539/jas.v4n9p209
Abstract: The objective of this work was to evaluate the performance of cover crops as for biomass production and nutrient accumulation during the crop off-season in an oxisol in Cerrado, in Goiás State, Brazil. The experiment was performed in Rio Verde, GO, Brazil, from November, 2007 to October, 2008. It was used a randomized block design, with plots divided according to time, with cover crops, and subplots, concerning biomass sampling, with four repetitions. The evaluated cover crops were: Brachiaria ruziziensis, Pennisetum glaucum and B. ruziziensis + Cajanus cajan, and as a reference, fallow treatment with sponteneous species. The biomass samples were collected five times, since the desiccation date of P. glaucum, 60 days after cover crop sowing, which occurred on June, 12th, 2008. The P. glaucum has shown the greatest amount of biomass and nutrient accumulation at 60 days after sowing, while the B. brizantha, B. ruziziensis and B. ruziziensis + C. cajan have shown significant accumulation in the end of the crop off-season.
Planting Date and Seeding Rate Effects on Sunn Hemp Biomass and Nitrogen Production for a Winter Cover Crop  [PDF]
Kipling S. Balkcom,Jessica M. Massey,Jorge A. Mosjidis,Andrew J. Price,Stephen F. Enloe
International Journal of Agronomy , 2011, DOI: 10.1155/2011/237510
Abstract: Sunn hemp (Crotalaria juncea L.) is a tropical legume that produces plant biomass and nitrogen (N) quickly. Our objectives were to assess the growth of a new sunn hemp cultivar breed to produce seed in a temperate climate and determine the residual N effect on a rye (Secale cereale L.) cover crop in east-central Alabama from 2007 to 2009. Plant populations, plant height, stem diameter, biomass production, and N content were determined for two sunn hemp planting dates, following corn (Zea mays L.) and wheat (Triticum aestivum L.) harvest, across different seeding rates (17, 34, 50, and 67?kg/ha). Rye biomass was measured the following spring. Sunn hemp biomass production was inconsistent across planting dates, but did relate to growing degree accumulation. Nitrogen concentrations were inversely related to biomass production, and subsequent N contents corresponded to biomass levels. Neither planting date nor seeding rate affected rye biomass production, but rye biomass averaged over both planting dates following wheat/sunn hemp averaged 43% and 33% greater than rye following fallow. Rye biomass following corn/sunn hemp was equivalent to fallow plots. Early planting dates are recommended for sunn hemp with seeding rates between 17 and 34?kg/ha to maximize biomass and N production. 1. Introduction Nitrogen (N) fertilizer costs are volatile and alternative N sources (such as legumes) are receiving renewed interest. In the southeastern United States, winter annual legumes are commonly incorporated into crop rotations and can contribute considerable biomass and N during the traditional winter fallow period. Legume biomass production is a major factor determining legume N contribution [1]. Nitrogen accumulation is highly variable and dependent upon environment, legume selection, planting date, termination, growth stage, and management strategy [1–3]. Throughout the Southeast, warm-season legumes, such as cowpea (Vigna unguiculata L.), sericea lespedeza (Lespedeza cuneata L.), and soybean (Glycine max L.) are currently available to producers for use as warm season cover crops, but they cannot produce substantial biomass or N in a short period of time. Sunn hemp, a nontraditional tropical legume, can also be used as a warm season cover crop across the Southeast. “Tropic Sun”, the most extensively studied cultivar, has been shown to produce 5.9?Mg/ha biomass and contribute 134–145?kg/ha N in a 9–12-week period [4]. This rapid biomass production enables sunn hemp to serve as a summer cover between warm-season harvest and cool-season planting that could also reduce
Quantifying methane emissions from rice paddies in Northeast China by integrating remote sensing mapping with a biogeochemical model
Y. Zhang, Y. Y. Wang, S. L. Su,C. S. Li
Biogeosciences (BG) & Discussions (BGD) , 2011,
Abstract: The Sanjiang Plain located in Northeastern China is one of the major rice producing regions in the country. However, differing from the majority rice regions in Southern China, the Sanjinag Plain possesses a much cooler climate. Could the rice paddies in this domain be an important source of global methane? To answer this question, methane (CH4) emissions from the region were calculated by integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition or DNDC. To quantify regional CH4 emissions from the plain, the model was first tested against a two-year dataset of CH4 fluxes measured at a typical rice field within the domain. A sensitivity test was conducted to find out the most sensitive factors affecting CH4 emissions in the region. Based on the understanding gained from the validation and sensitivity tests, a geographic information system (GIS) database was constructed to hold the spatially differentiated input information to drive DNDC for its regional simulations. The GIS database included a rice map derived from the Landsat TM images acquired in 2006, which provided crucial information about the spatial distribution of the rice fields within the domain of 10.93 million ha. The modeled results showed that the total 1.44 million ha of rice paddies in the plain emitted 0.48–0.58 Tg CH4-C in 2006 with spatially differentiated annual emission rates ranging between 38.6–943.9 kg CH4-C ha 1, which are comparable with that observed in Southern China. The modeled data indicated that the high SOC contents, long crop season and high rice biomass enhanced CH4 production in the cool paddies. The modeled results proved that the northern wetland agroecosystems could make important contributions to global greenhouse gas inventory.
Quantifying methane emissions from rice paddies in Northeast China by integrating remote sensing mapping with a biogeochemical model  [PDF]
Y. Zhang,Y. Y. Wang,S. L. Su,C. S. Li
Biogeosciences Discussions , 2011, DOI: 10.5194/bgd-8-385-2011
Abstract: The Sanjiang Plain located in Northeastern China is one of the major rice producing regions in the country. However, differing from the majority rice regions in Southern China, the Sanjinag Plain possesses a much cooler weather. Could the rice paddies in this domain be an important source of global methane? To answer this question, we calculated methane (CH4) emissions from the region by integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition or DNDC. To quantify regional CH4 emissions from the plain, we first tested the model against a two-year dataset of CH4 fluxes measured at a typical rice field within the domian. A sensitivity test was conducted to find out the most sensitive factors affecting CH4 emissions in the region. Based on the understanding gained from the validation and sensitivity tests, a geographic information system (GIS) database was constructed to hold the spatially differentiated input information to drive DNDC for its regional simulations. The GIS database included a rice map derived from the Landsat TM images, which provided crucial information about the spatial distribution of the rice fields within the domain of 10.93 million hectares. The modeled results showed that the total 1.44 million ha of rice paddies in the plain emitted 0.43–0.58 Tg CH4-C per year with spatially differentiated annual emission rates ranging between 100–800 kg CH4-C/ha, which are comparable with that observed in Southern China. The modeled data indicated that the high SOC contents, long crop season and high rice biomass enhanced CH4 production in the cool paddies. The modeled results proved that the northern wetland agroecosystems could make important contributions to global greenhouse gas inventory.
Direct and residual effect of zinc and zinc amended organic manures on the zinc nutrition of field crop
Shelley Gupta,Kalpana Handore
International Journal of Agriculture Sciences , 2009,
Abstract: Zinc (Zn) deficiency is the most widespread micronutrient disorder in rice (Oryza sativa) Theobjective of this paper was to examine alternative evaluation methods and to identify the most informativetraits that would provide realistic information for rice breeders and to map quantitative trait loci (QTLs)associated with tolerance The most severe symptom in the field was high plant mortality. Zinc interfered withtranslocation of iron from roots to above ground parts of Glycine max. (L.) Merrill var. Hawkeye. Duringperiods in which zinc impeded iron translocation, it also suppressed the production of reductant by roots.Addition of iron, as a ferric metal chelate (iron ethylenediaminedihydroxyphenylacetic acid), to the growthmedium overcame the interference of zinc. In the root epidermis, potassium ferricyanide formed a precipitate(Prussian blue) with ferrous iron derived from the previously supplied ironethylenediaminedihydroxyphenylacetic acid. The reduction of ferric iron was suppressed by zinc. In a fieldexperiment on silt loam calcareous soil, the direct and residual effect of zinc and zinc amended organicmanures were studied on rice (Oryza sativa L.) followed by barley (Hordeum vulgare L.) and ricerespectively. Visual Zn deficiency symptoms were observed on rice in on zinc plots. Application of zincsignificantly increased the crop yield. The magnitude of yield response was intensified where zinc wasapplied in conjunction with organic manures. The highest Zn uptake in these three crops was recorded at 5kg Zn amended with 10t compost /ha.
The Present Status of the Emission Methane in China
中国甲烷排放现状

Zhang Renjian,Wang Mingxing,Li Jing,Yang Xin,Wang Xiuling,
张仁建
,王明星,李晶,杨昕,王秀玲

气候与环境研究 , 1999,
Abstract: The emission of methane in China in 1990 and 1994 is estimated Firstly, the emission of methane in 1990 is collected and improved, especially the emission of methane from landfill is calculated Secondly, the emission of methane in 1994 is calculated according to the updated data Results show that the emission of methane in 1990 and 1994 are 30 92 Tg, and 32 91 Tg respectively The emission of methane from coal mining, oil and gas, animal manure and biomass domestic livestock increases while the emission of methane from biomass fuel and flooded rice fields decreases in 1994 compared with that in 1991 There is no great change of methane emission from the compost
Mitigation of methane and nitrous oxide emissions from flood-irrigated rice by no incorporation of winter crop residues into the soil
Zschornack, Tiago;Bayer, Cimélio;Zanatta, Josiléia Acordi;Vieira, Frederico Costa Beber;Anghinoni, Ibanor;
Revista Brasileira de Ciência do Solo , 2011, DOI: 10.1590/S0100-06832011000200031
Abstract: winter cover crops are sources of c and n in flooded rice production systems, but very little is known about the effect of crop residue management and quality on soil methane (ch4) and nitrous oxide (n2o) emissions. this study was conducted in pots in a greenhouse to evaluate the influence of crop residue management (incorporated into the soil or left on the soil surface) and the type of cover-crop residues (ryegrass and serradella) on ch4 and n2o emissions from a flooded albaqualf soil cultivated with rice (oryza sativa l.). the closed chamber technique was used for air sampling and the ch4 and n2o concentrations were analyzed by gas chromatography. soil solution was sampled at two soil depths (2 and 20 cm), simultaneously to air sampling, and the contents of dissolved organic c (doc), no3-, nh4+, mn2+, and fe2+ were analyzed. methane and n2o emissions from the soil where crop residues had been left on the surface were lower than from soil with incorporated residues. the type of crop residue had no effect on the ch4 emissions, while higher n2o emissions were observed from serradella (leguminous) than from ryegrass, but only when the residues were left on the soil surface. the more intense soil reduction verified in the deeper soil layer (20 cm), as evidenced by higher contents of reduced metal species (mn2+ and fe2+), and the close relationship between ch4 emission and the doc contents in the deeper layer indicated that the sub-surface layer was the main ch4 source of the flooded soil with incorporated crop residues. the adoption of management strategies in which crop residues are left on the soil surface is crucial to minimize soil ch4 and n2o emissions from irrigated rice fields. in these production systems, ch4 accounts for more than 90 % of the partial global warming potential (ch4+n2o) and, thus, should be the main focus of research.
Enzyme activity and microbial biomass in an Oxisol amended with sewage sludge contaminated with nickel
Revoredo, Marcos Donizeti;Melo, Wanderley José de;
Scientia Agricola , 2007, DOI: 10.1590/S0103-90162007000100009
Abstract: the role of nickel in soils of tropical areas under the application of sewage sludge is still not very well known. this study was carried out under greenhouse conditions in jaboticabal, s?o paulo state, brazil, with the objective of evaluating the impact of the application of sewage sludge previously contaminated with rates of nickel (329, 502, 746 and 1119 mg kg-1, dry basis) on a soil cropped with sorghum, in relation to soil enzyme activity and soil microbial biomass. soil samples were collected at the beginning and the end of the experiment. the experimental design was completely randomized, with five treatments (control and four rates of ni in the sewage sludge) and four replications. c and n of the soil microbial biomass and enzyme activities (acid and alkaline phosphatases) were sensitive indicators for impact evaluation caused by sewage sludge contaminated with nickel. there were positive correlations between "total" and extractable nickel (mehlich 1) with c-microbial biomass and negative with the microbial c/n relationship. n-microbial biomass correlated positively with "total" and extractable ni at the last sampling. at the end of the experiment, the acid phosphatase activity correlated negatively with "total" ni while the alkaline phosphatase correlated with both forms of the metal.
Crop Residue Biomass Effects on Agricultural Runoff  [PDF]
Damodhara R. Mailapalli,Martin Burger,William R. Horwath,Wesley W. Wallender
Applied and Environmental Soil Science , 2013, DOI: 10.1155/2013/805206
Abstract: High residue loads associated with conservation tillage and cover cropping may impede water flow in furrow irrigation and thus decrease the efficiency of water delivery and runoff water quality. In this study, the biomass residue effects on infiltration, runoff, and export of total suspended solids (TSS), dissolved organic carbon (DOC), sediment-associated carbon (TSS-C), and other undesirable constituents such as phosphate (soluble P), nitrate ( ), and ammonium ( ) in runoff water from a furrow-irrigated field were studied. Furrow irrigation experiments were conducted in 91 and 274?m long fields, in which the amount of residue in the furrows varied among four treatments. The biomass residue in the furrows increased infiltration, and this affected total load of DOC, TSS, and TSS-C. Net storage of DOC took place in the long but not in the short field because most of the applied water ran off in the short field. Increasing field length decreased TSS and TSS-C losses. Total load of , , and soluble P decreased with increasing distance from the inflow due to infiltration. The concentration and load of P increased with increasing residue biomass in furrows, but no particular trend was observed for and . Overall, the constituents in the runoff decreased with increasing surface cover and field length. 1. Introduction The USA, having more than 408 million acres of crop land and an abundant supply of food products, is noted worldwide for its high productivity, quality and efficiency in delivering goods to the consumer [1]. However, the agricultural practices used to produce these quality products are affecting the sustainability of crop production systems and impacting water quality in many regions of the country. Agriculture is the third leading source of pollution in USA estuaries [2]. Specifically, elevated dissolved organic carbon (DOC) concentrations in runoff that finds its way to main drinking water supplies are of significant concern because of serious potential health concerns. During chlorination to produce drinking water, a subgroup of DOC, or disinfection byproduct precursors, form disinfection byproducts (DBPs), of which trihalomethanes and haloacetic acids are the most abundant. These DBPs, stringently regulated by the USEPA, are carcinogenic and mutagenic. Therefore, knowledge of water quality parameters such as nutrients, sediments, and bacterial concentrations of flooded fields is important, because the water released from these fields eventually flows into streams and rivers. One of the important methods of controlling pollution by agricultural
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