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Browsing by Author "Bruns, Wendy A."

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    Bowen Ratio Energy Balance Measurement of Carbon Dioxide (CO2) Fluxes of No-Till and Conventional Tillage Agriculture in Lesotho
    O'Dell, Deb; Sauer, Thomas J.; Hicks, Bruce B.; Lambert, Dayton M.; Smith, David R.; Bruns, Wendy A.; Basson, August; Marake, Makoala V.; Walker, Forbes; Wilcox, Michael D.; Eash, Neal S. (Open Journal of Soil Science, 2014)
    Global food demand requires that soils be used intensively for agriculture, but how these soils are managed greatly impacts soil fluxes of carbon dioxide (CO2). Soil management practices can cause carbon to be either sequestered or emitted, with corresponding uncertain influence on atmospheric CO2 concentrations. The situation is further complicated by the lack of CO2 flux measurements for African subsistence farms. For widespread application in remote areas, a simple experimental methodology is desired. As a first step, the present study investigated the use of Bowen Ratio Energy Balance (BREB) instrumentation to measure the energy balance and CO2 fluxes of two contrasting crop management systems, till and no-till, in the lowlands within the mountains of Lesotho. Two BREB micrometeorological systems were established on 100-m by 100-m sites, both planted with maize (Zea mays) but under either conventional (plow, disk-disk) or no-till soil management systems. The results demonstrate that with careful maintenance of the instruments by appropriately trained local personnel, the BREB approach offers substantial benefits in measuring real time changes in agroecosystem CO2 flux. The periods where the two treatments could be compared indicated greater CO2 sequestration over the no-till treatments during both the growing and non-growing seasons.
  • Carbon sequestration in a tilled and untilled maize field in Lesotho, Southern Africa
    Bruns, Wendy A.; Eash, Neal S.; Sauer, T.; Walker, Forbes; West, T. O.; Marake, Makoala V.; Lambert, Dayton M.; Wilcox, Michael D.; Bruns, M. (2015-01-22)
    This presentation was given at the Soil Science Society of America annual meeting on October 19th, 2011 in San Antonio Texas at 10:05 in the morning. No-till agriculture was practiced in Lesotho, Southern Africa, while observing the amount of carbon emissions in the atmosphere during the growing season. Comparisons were made between land under no-till and crop rotation management and land practicing plowed.
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    Developing sustainable subsistence smallholder conservation agricultural systems in Lesotho
    Eash, Neal S.; Walker, Forbes; Lambert, Dayton M.; Wilcox, Michael D.; Marake, Makoala V.; Wall, Patrick; Basson, August; Bruns, Wendy A.; Bruns, M. (2011)
    The average subsistence maize yield in Lesotho is very low (less than 0.3 Mg/ha) due to excessive soil erosion rates, low soil fertility, high fertilizer and herbicide cost, moisture/nutrient loss from weed competition, and high labor requirements for hand weeding. The break-even yields for subsistence farmers are approximately 2 Mg/ha or approximately seven times the average yield. This study was conducted to determine the economically viable nitrogen and phosphorus fertilizer rates, planting density, cover crop weed suppression effectiveness, and cultivation methods for maize production. The soils at the experiment site were silty clay loam and located near Mohale's Hoek. The 2009 results indicated that the most expensive smallholder farming method was the hired tractor or animal draft that used hired labor for weeding and was followed closely by likoti ('pothole' method). The most cost effective method was the use of no-till planter. Cover crops suppressed up to 90% of Common Thistle and Cape Tulip (Moraea flaccida), with Grazing Vetch (Vicia sativa) the most effective weed suppressor. Both higher N and P rates and population densities are needed because yields continued to increase at the higher fertilizer rates and population densities. Results from the first year of data suggest that cover crops will be an important component in weed control. Fertilizer N and P rates need to be increased as do the target plant populations.
  • Energy balance and carbon dioxide flux in conventional and no-till maize fields in Lesotho, Southern Africa
    Bruns, Wendy A. (2012)
    The capacity of soils to sequester carbon is currently of scientific interest because soil management impacts carbon dioxide flux and can mitigate the effects of climate change. Soil carbon sequestration is also essential in areas with degraded soil where land use is primarily subsistence agriculture because of limited inputs to increase fertility and return soil nutrients removed during crop growth. Agricultural soils under no-till management can increase soil carbon levels compared to soils managed with traditional tillage practices in the long-term (decades); this is hypothesized to be caused by the short-term (i.e., seasonal) flux of carbon dioxide between the terrestrial system and the atmosphere. In order to investigate the potential of no-till agricultural systems to increase soil carbon in sub-Saharan Africa, micrometeorological stations were set up during the growing season in two adjacent fields with soils classified as Phechela series (fine, montmorillonitic, mesic Typic Pelludert). The fields were located near the village of Maphutseng outside of Mohale’s Hoek, Lesotho (lat. -30.213, long. 27.496, 1456 m above mean sea level). The study area is in the lowland agroecological zone of Lesotho, with long-term mean annual precipitation of approximately 800 mm/yroccuring primarily during the warm summer season between October and March. These stations continuously record the environmental components necessary to complete the Bowen’s ratio energy balance equations for the fields, of which both are cropped in maize-soybean rotations, one under no-till management and the other plowed. Comparison of the transfer of energy throughout the two different cropping systems over the course of the cropping cycle may indicate the suspected superiority of no-till systems for maximizing carbon dioxide uptake of agricultural systems over time, but further data collection is necessary in order to establish significant trends.