• Authors:
    • Lokhande, S.
    • Reddy, K. R.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 4
  • Year: 2014
  • Summary: Quantitative functional relationships between temperature and fiber quality are needed to improve predictive capability of cotton ( Gossypium hirsutum L.) models. An experiment was conducted by varying day/night temperatures, 22/14, 26/18, 30/22, and 34/26°C, imposed at flowering. Upland cotton cultivar, TM-1, was seeded in the soil bins using fine sand as the rooting medium and allowed to grow under optimum water and nutrients. Flowers and bolls were tagged daily to estimate the boll maturation period. Plant height and node numbers were recorded from emergence to 21 d after treatment. Stem, leaf, boll dry weights, and boll numbers were recorded at maturity. Measured fiber quality parameters were regressed against temperature to develop mathematical functions for modeling. The optimum temperature for biomass was between 18.1 and 21.5°C and biomass declined by 10% at 25.5°C and 19% at 29.5°C. More bolls were produced at 25.5°C, but declined sharply at 29.5°C. Reproductive potential, boll mass per unit total weight, peaked at 25.5°C and was lower by 21% at 18.1°C and 53% at 29.5°C. Fiber micronaire and uniformity increased with temperature up to 26°C and declined at higher temperature, while fiber strength increased linearly with temperature. Fiber length increased linearly from 18 to 22°C, and declined at higher temperatures. Fiber micronaire was more responsive to changes in temperature followed by strength, length, and uniformity. The functional relationships between temperature and fiber properties will be useful to optimize management decisions such as planting dates and to develop fiber submodel under optimal water and nutrient conditions.
  • Authors:
    • Stahlman, P. W.
    • Benjamin, J. G.
    • Mikha, M. M.
    • Geier, P. W.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 1
  • Year: 2014
  • Summary: Nutrient dynamics in the calcareous eroded soils of the western United States may react differently than the acid soils in the eastern United States. The objectives of this study were to evaluate the impact of tillage practices and N treatments on changes in soil nutrient constituents. The eroded study was initiated in 2006 at the Agriculture Research Center, Hays, KS, on an Armo silt loam (fine-loamy, mixed, mesic Entic Haplustolls). Tillage practices were no-tillage (NT) and conventional tillage (CT). Beef manure (M) and urea, as commercial fertilizer (F) at low (L) and high (H) rates were applied as N sources. The control (C) treatment, with no N added, was included under both tillage practices. Annually (2006-2011) spring soil samples were taken at 0- to 15-cm and 15- to 30-cm depths. Soil chemical properties were influenced by N treatments and sampling depths, but not by tillage. Soil acidity (pH) was reduced in 2011 compared with 2006. Relative to control, more reduction in soil pH was observed with HM (21%) compared with HF treatment. Soil EC with HM and HF was approximately 2.2 times greater than LM and LF. Soil extractable P with HM substantially increased, 45.9 mg kg -1, compared with LM, 18.3 mg kg -1, at the surface 0 to 15 cm. The change in soil organic carbon (DeltaSOC) associated with M was 36-fold higher than F treatments. In general, the use of M as N source improved soil nutrient dynamics in this eroded site compared with F.
  • Authors:
    • Benjamin, J. G.
    • Stahlman, P. W.
    • Mikha, M. M.
    • Geier, P. W.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 1
  • Year: 2014
  • Summary: The response of manure applications on calcareous eroded soils in the western United States is unlike the responses observed on acid soils in the eastern United States. The objectives of this study were to restore the productivity and evaluate N loss of eroded land influenced by tillage practices, N sources, and N rates. The study was initiated in 2006 on an Armo silt loam (fine-loamy, mixed, mesic Entic Haplustolls) at the Agriculture Research Center, Hays, KS. Tillage practices were no-tillage (NT) and conventional tillage (CT). Nitrogen sources were beef manure (M); urea, as commercial fertilizer (F); and no-N control (C) at two rates, low (L) and high (H). The crop rotation was grain sorghum ( Sorghum bicolor L.), forage oat ( Avena sativa L.), winter wheat ( Triticum aestivum L.), grain sorghum, proso millet ( Panicum miliaceum L.), and winter wheat. Grain yield (2006-2011) and soil inorganic nitrogen (SIN) at 0- to 120-cm depth were evaluated. Grain yields were not influenced by tillage practices, except in 2006 when NT had greater yields than CT. Manure addition increased grain yields compared with F and C treatments. Excess amounts of N and low productivity lead to leaching of the SIN down the soil profile with HF and HM. The LM exhibited less productivity and less SIN loss than HM treatment. Overall, M could be the N source that can improve the productivity of the eroded site. The benefits of increasing the productivity and the risk of N loss with HM need to be further addressed.
  • Authors:
    • Mekuria, M.
    • Aune, J. B.
    • Johnsen, F. H.
    • Ngwira, A.
    • Thierfelder, C.
  • Source: Journal of Soil and Water Conservation
  • Volume: 69
  • Issue: 2
  • Year: 2014
  • Summary: Understanding factors affecting farmers' adoption of improved technologies is critical to success of conservation agriculture (CA) program implementation. This study, which explored the factors that determine adoption and extent of farmers' use of the three principles of CA (i.e., minimum soil disturbance, permanent soil cover with crop residues, and crop rotations), was conducted in 10 target communities in 8 extension planning areas in Malawi. The primary data was collected using structured questionnaires administered to individual households. Triangulation with key informant interviews, field observations, and interactive discussions with farmers and farmer groups provided information behind contextual issues underpinning the statistical inferences. From a total of 15,854 households in the study areas, it is estimated that 18% of the smallholder farmers had adopted CA, representing an area of about 678 ha (1,675 ac; 2.1% of all cultivated land). Land area under CA constituted about 30% of total cultivated land among adopters. A random sample of 151 adopters and 149 nonadopters proportional with respect to adoption rates was drawn from various communities and interviewed using structured questionnaires. A total of 30 key informant interviews were conducted with stakeholders including staff of Total Land Care, government extension workers, agroinput suppliers, and lead farmers. The first stage of the Heckman model showed that hired labor, area of land cultivated, membership to farmer group, and district influenced farmers' decisions to adopt CA. The second stage of Heckman model results suggested that total cultivated land, duration of practicing CA, and district influenced farmers' decisions to extend their land to CA. Our study can be used to show the agency and social structures that are likely to influence adoption and extent of CA. Future policy should address ways to provide access to information and long-term support to farmers to enable them to embrace the technology fully.
  • Authors:
    • Urquiaga, S.
    • Boddey, R. M.
    • Sant'Anna, S. A. C. de
    • Lessa, A. C. da R.
    • Paredes, D. da S.
    • Alves, B. J. R.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 98
  • Issue: 1
  • Year: 2014
  • Summary: In Brazilian sugarcane plantations, fertilization with vinasse, supplemented or not with mineral fertilizer, is a common practice. But little is known about the effects of this application on N losses, especially those forms of N which give rise to greenhouse gas emissions. The aim of this study was to quantify N2O and NH3 emissions from soil after vinasse application and urea fertilizer addition and to examine the possible impact adding vinasse before or after urea. Two experiments were conducted under greenhouse conditions and one in the field with treatments of vinasse and urea fertilizer, either alone, or in sequence. The highest proportions of N emitted as N2O were registered in the vinasse treatment, which amounted to 15 % of the N applied in the first greenhouse experiment, and 2.5 % in the field experiment. With respect to the losses by NH3 volatilization, urea was the only treatment where this process was significant. N2O emission from vinasse was 2.5 %, somewhat above the default emission factor of 1 % of the IPCC. N2O emissions from urea were also variable, but emission factors registered were still well below the default IPCC factor for organic residues. The order of addition of urea and vinasse had little effect on NH3 volatilization in the field, but there were evidences it was important for N2O.
  • Authors:
    • Meisinger, J. J.
    • Pote, D. H.
  • Source: Journal of Soil and Water Conservation
  • Volume: 69
  • Issue: 1
  • Year: 2014
  • Summary: Ammonia (NH3) volatilization from agricultural fields is important economically as a direct loss of the valuable crop nutrient nitrogen (N), but it can also be a significant environmental concern for soil, air, and water quality of nearby ecosystems. As poultry production has expanded in cropland areas of the southeastern United States, poultry litter has become a major source of crop nutrients for farmers using conservation tillage systems. However, the conventional application method of broadcasting poultry litter on the soil surface can allow as much as 60% of the applied litter N to volatilize as NH3. To provide management options that can prevent NH3 losses and help farmers use poultry litter nutrients more efficiently, a research team at USDA's Agricultural Research Service developed a prototype tractor-drawn implement for subsurface application of dry poultry litter in perennial pasture and conservation tillage systems. When compared to surface broadcasting, previous research showed that subsurface application of poultry litter decreased odor problems, increased crop yields, prevented more than 90% of nutrient losses in runoff, and prevented NH3 volatilization from perennial pasture systems. The current study was conducted to expand our knowledge regarding the effect of this litter application method on NH3 volatilization from row-crop conservation tillage systems. For two consecutive summers, field plots with a uniform high-residue surface cover of chopped wheat straw received about 5,000 kg ha(-1) (4,500 lb ac(-1)) of poultry litter applied by surface spreading with no incorporation, surface spreading followed by light disking, or subsurface banding using the prototype USDA ARS applicator. Small mobile wind tunnels monitored NH3 volatilization for at least five days after each litter treatment. Results for both years showed that NH3 losses were consistently affected by diurnal variations that were closely related to the vapor pressure deficit. Compared to conventional surface spreading of poultry litter, NH3 volatilization decreased an average of 67% when the litter application was followed by light disking, and decreased an average of 88% when the litter was applied below the soil surface using the prototype applicator. These data show that subsurface injection of dry poultry litter can preserve adequate surface cover for conservation needs while constraining NH3 losses to minimal levels, thus conserving N for row crops and reducing potential nitrogen losses to the environment.
  • Authors:
    • Carvalho, P. C. de F.
    • Anghinoni, I.
    • Assmann, J. M.
    • Ferreira, A. O.
    • Amado, T. J. C.
    • Silva, F. D. da
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 190
  • Year: 2014
  • Summary: Brazil has the world's second-largest cattle herd and second-largest no-till grain crop area. However, these activities are not frequently integrated because there is a widespread perception that cattle have a negative effect on cropping, especially when high crop yields are a goal. This misunderstanding of the synergy between pastures, livestock and crops is linked to overgrazing at the pasture rotation phase, which causes a decline in soil quality. Few studies have investigated the effect of pasture grazing intensities on soil carbon (C) balance and soil quality in subtropical environments. This work assessed the effects of different grazing intensities (0.10, 0.20, 0.30 and 0.40 m sward height) on soil C indices and animal productivity in a clay Haplorthox. The crop-livestock system model was a soybean/ryegrass plus black oat annual rotation managed for 10 years, using a randomized complete block design with three replications. Grazing intensity affected the quantity and composition of soil C input. Under heavy grazing with limited soil C input, there was a decrease in pasture and an increase in soybean participation in total C input. Soil organic C (0-0.20 m) under different grazing intensities had a linear relationship with C stratification ratio, C management index (CMI) and C pool index. Our results suggest that integrated crop-livestock systems could act as atmospheric C sources or sinks, depending on the grazing intensity. Pastures managed at 0.20 and 0.40 m height had the best balance between CMI and animal daily gain. The best balance between CMI and live weight gain per unit area occurred in sward height of 0.20 m.
  • Authors:
    • Guzman, J. A.
    • Steiner, J. L.
    • Garbrecht, J. D.
    • Grimsley, D. L.
    • Fiebrich, C. A.
    • Starks, P. J.
    • Moriasi, D. N.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 4
  • Year: 2014
  • Summary: Hydrologic, watershed, water resources, and climate-related research conducted by the USDA-ARS Grazinglands Research Laboratory (GRL) are rooted in events dating back to the 1930s. In 1960, the 2927-km 2 Southern Great Plains Research Watershed (SGPRW) was established to study the effectiveness of USDA flood control and soil erosion prevention programs. The size of the SGPRW was scaled back in 1978, leaving only the 610-km 2 Little Washita River Experimental Watershed (LWREW) to be used as an outdoor hydrologic research laboratory. Since 1978, the number of measurement sites and types of instruments used to collect meteorologic and soil climate data have changed on the LWREW. Moreover, a second research watershed, the 786-km 2 Fort Cobb Reservoir Experimental Watershed (FCREW), was added in 2004 to the GRL's outdoor research laboratories to further study the effects of agricultural conservation practices on selected environmental endpoints. We describe the SGPREW, FCREW, and LWREW and the meteorologic measurement network (historic and present) deployed on them, provide descriptions of measurements, including information on accuracy and calibration, quality assurance measures (where known), and data archiving of the present network, give examples of data products and applications, and provide information for the public and research communities regarding access and availability of both the historic and recent data from these watersheds.
  • Authors:
    • Nalley, L. L.
    • Barkley, A.
    • Tack, J.
  • Source: Climatic Change
  • Volume: 125
  • Issue: 3-4
  • Year: 2014
  • Authors:
    • Smith, C.
    • Dargusch, P.
    • Visser, F.
    • Grace, P. R.
  • Source: Agroecology and Sustainable Food Systems
  • Volume: 38
  • Issue: 8
  • Year: 2014
  • Summary: An increasing concern over the sustainability credentials of food and fiber crops require that farmers and their supply chain partners have access to appropriate and industry-friendly tools to be able to measure and improve the outcomes. This article focuses on one of the sustainability indicators, namely, greenhouse gas (GHG) emissions, and nine internationally accredited carbon footprint calculators were identified and compared on an outcomes basis against the same cropping data from a case study cotton farm. The purpose of this article is to identify the most "appropriate" methodology to be applied by cotton suppliers in this regard. From the analysis of the results, we subsequently propose a new integrated model as the basis for an internationally accredited carbon footprint tool for cotton and show how the model can be applied to evaluate the emission outcomes of different farming practices. © Taylor & Francis Group, LLC.