Thesis (M. Sc. Agriculture (Soil Science)) -- University of Limpopo, 2015 / The activity and functional diversity of micro-organisms contribute to the stability and productivity of agro-ecosystems. Soil micro-organisms and enzyme activities have been suggested as potential indicators of soil quality. Hence, management practices that can enhance microbial diversity and enzyme activities are essential for improving soil health and soil fertility status. The aim of the study was to assess the effects of compost maturity age on the change in bio-quality indicators of compost and compost amended soil. Cattle manure-rich compost was prepared through thermophilic windrow composting using cattle manure and wood chips mixed at a proportion of 4:1 (w/w) to achieve a C:N ratio of 30:1. This compost was sampled at regular intervals of 30 days after the initiation of the composting process until 150 days when it was finally cured. Compost samples of varying degrees of maturity age were air-dried, pulverised and mixed with 1.2 kg surface soil at an equivalent rate of 100 kg P ha-1. Each compost amended soil was transferred into well labelled plastic pots for incubation. Sampling of incubated amended soils was performed at 7 days interval until 42 days; and the samples were used for microbial count, enzyme activity, and mineralisation assessments. Data generated were analysed as factorial experiment using SYSTAT package. Treatment and interaction effects were evaluated using Fisher protected least significant difference at probability level of 5%. Results of the chemical composition of the different composts are similar and comparable. Variation in compost maturity date, incubation time and their interaction exerted significant effects on the measured microbial counts and enzyme activities as bio-quality indicators. The content of bacteriameasured was consistently highest at each sampling date followed by the actinomycetes while fungi population count remained persistently lowest. Bacteria and β-glucosidase represent the dominant microbe and enzyme, respectively in all compost samples taken at different maturity age.The highest count of actinomycetes (6.18 CFU g-1), bacterial (6.73 CFU g-1) and fungi (3.06 CFU g-1) were obtained during the 42-day incubation period.Of all the enzyme activities studied, β-glucosidase content was consistently highest in all compost samples across the sampling dates. Similarly, the highest concentration of ß-glucosidase (3076 mg kg-1 hr-1), phosphatase (1480 mg kg-1 hr-1), dehydrogenase iv (120.07 μg INF g-1 2hr-1) and urease (26.15 mg kg-1 2hr-1) were obtained during the 42-day incubation period. The highest microbial counts and enzyme activities were reached beyond 19 days after incubation. Maximum Bray P1 (20.10 mg kg-1), ammonium N (108 mg kg-1) and nitrate N (189 mg kg-1) were obtained at 42, 14 and 42 days after incubation, respectively. The measured temporal change in the concentrations of bio-quality parameters in the compost-amended soils were highest in compost sampled at 90 days, except for phosphatase, indicating the peak of the thermophilic process. The bio-quality parameters of these composts and the compost amended soil were influenced by compost maturity and incubation time. The uses of mature compost with desirable level of bio-quality indicators are crucial for fertility management and improved soil health. Keywords: Compost maturity, enzyme activities, microbial count, nutrient release, soil fertility

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第22865号 / 地環博第204号 / 新制||地環||39(附属図書館) / 京都大学大学院地球環境学舎環境マネジメント専攻 / (主査)准教授 真常 仁志, 教授 舟川 晋也, 教授 藤井 滋穂 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

The principal objective of this project was to evaluate the short-term effects of CBW incorporation into soil in terms of soil fertility, plant growth and soil microbiology. Treatments consisted of a control, standard woodchip treatment (incorporation rate of 150m3/ha), woodchip + woodland litter incorporation treatment (woodland litter incorporation of 10-20g/m2), woodchip + fertiliser treatment (KNO3 applied at 50kgN/ha at start and a continuous fertiliser application treatment) and double woodchip treatment. Standard soil NO-3 tests were conducted to determine soil fertility. To assess plant growth and development, plant DW, S:R DW and plant K levels were measured Finally, microbiological analyses were carried out through serial dilutions and plate counts, with in-depth microscopy. Results indicated that there were obvious differences between treatments throughout the study period. In all measurements, woodchip treatments were found to have significantly lower values than the control. The exception to the rule was the WC + fertiliser treatment (continuous complete nutrient fertiliser application), which showed comparable results with the control. The addition of woodland litter did not seem to affect any of the soil fertility, plant growth or microbial measurements. The differences between the unfertilised woodchip treatments and the control were explained by a general nutrient deficiency resulting from a ‘dilution effect’ to soil nutrients by adding woodchips. This was further exacerbated by immobilisation of nutrients from the micro-organisms in the soil.

The main objective of this study was to evaluate the organic N in silty clay loam soil as an indicator of soil fertility. The incubation method was used in this study. The N03 -N, the total N percent, and the organic matter were determined. The soil which was used in this study came from Evans Research Farm. The samples were taken from two different N experiments which were adjacent to each other. The soil samples were taken in October-November, 1973, after the crop had been harvested. These two experiments had different cropping histories. The results of the first experiment which had continuous corn for four years indicated that there was no correlation between the mineralizable-N and the crop performance, but there was a good correlation between the No3 -N and crop yield. The results of the second experiment which had alfalfa for three years prior to corn indicated that there was a good correlation between N03-N and the crop performance and also there was a correlation between mineralizable-N and crop performance. It was concluded that cropping history could be used as a guideline as to whether mineralizable-N should be tested as an indication of soil N availability. In situations where the cropping history is unknown, N03-N could be used exclusively since it was a good fertility predictor in both of these field experiments.

No description available.

Iron deficiency chlorosis (IDC) is a frequent problem in soybean [Glycine max (L.) Merr.] production on calcareous soils. Greenhouse and soil incubation experiments were established to evaluate pyritic lignite efficacy to supply Fe as compared to Fe-EDDHA and Fe-EDTA sources across contrasting IDC tolerance varieties grown on a slightly acid and a calcareous soil. Soybean IDC incidence was influenced by the soil properties and variety tolerance. All iron sources increased plant dry matter accumulation on the Leeper soil, whereas on the Marietta soil only lignite at 0.672 kg ha-1 produced an increase. Lignite at 0.336 kg ha-1 successfully improved Fe availability to the plant as reflected by an increase in Fe content. Furthermore, no differences were found between the low rate of lignite and the commercial fertilizers on any of the evaluated parameters. Results from this study indicate that pyritic lignite may serve as an acceptable source of Fe on problem soils to prevent IDC.

No description available.

Drought, salinity, and low soil fertility have negative impacts on agricultural productivity, resulting in food scarcity and nutritional insecurity, particularly in Sub-Saharan Africa. Mungbean [Vigna radiata (L.) R. Wilczek] has seen increased interest as a short-duration and drought tolerant legume crop, capable of atmospheric N₂ fixation. Mungbean is a protein and iron-rich legume and can be used as vegetable or grain for human consumption or multipurpose crop. At present, few studies have simultaneously explored the best agronomic practices for mungbean cultivation and evaluated its potential for increasing crop yields via intercropping systems and improving soil fertility through biological N₂ fixation. To understand the agronomic practices and soil physical properties limiting mungbean production, the impacts of two mungbean cultivars (Berken and OK2000) with and without inoculation with Bradyrhizobium spp. grown in loamy sand and silt loam soils on mungbean growth and yield were investigated under glasshouse conditions. Promising results from this study led to the introduction of mungbean into pearl millet systems in Senegal and evaluation of the effects of intercropping on growth, yields, land equivalent ratio (LER), canopy cover estimates, and normalized difference vegetation index (NDVI). Finally, we evaluated plant growth and N₂ fixation of five mungbean genotypes grown in two soil textures using the ¹⁵N natural abundance technique leading to recommendations for those with the greatest overall benefit to the cropping system. The literature review shows mungbean often proposed as a strategic crop for increasing legume diversification within current cropping systems and providing increased food security as well as market diversification and economic sustainability. The greenhouse study revealed that OK2000 cultivar produced significantly higher yield when inoculated and planted on a silt loam soil than other treatments, indicating the importance of inoculation and soil texture in mungbean establishment. Intercropping mungbean and millet significantly (p≤ 0.05) increased combined yields (35% to 100% increase) and LER compared to sole millet cropping systems. Canopy cover estimates and NDVI values significantly increased up to 60% and 30%, respectively, in millet-mungbean intercropping over millet alone. The N2 fixation study showed that %Ndfa of mungbean was higher when grown in the loamy sand soil (27% increase). However, soil N uptake (235 mg plant⁻¹) and amount of N fixed (67 mg plant⁻¹) were greater in the silt loam soil. Among genotypes, IC 8972-1 significantly (p≤ 0.05) derived less N from the atmosphere (23%) but took more soil N (155 mg plant⁻¹) which yielded significantly greater dry biomass (7.85 g plant⁻¹) and shoot N content (200 mg plant⁻¹). The results from the N₂ fixation study indicated that choice of mungbean genotype can contribute to reducing N needs of agricultural systems. Overall, this research project demonstrated that mungbean has the potential for diversifying smallholder agriculture and adding biologically fixed N into soils, in line with transformative adaptation strategies being promoted for sustainable agriculture. Further research and development programs on good cultural practices, adaptation to cropping systems, and nutritional benefits for human consumption can promote mungbean cultivation in SSA. / Doctor of Philosophy / Global population growth is expected to reach 9.8 billion in 2050 while climate change is predicted to reduce food production. Sustainable solutions are needed for increasing food availability and satisfying nutritional needs under changing climatic conditions. Mungbean is a viable option because it is a legume crop capable of restoring soil fertility and has low water requirements. Mungbean also contains high levels of protein and iron and can, therefore, provide a nutritious and healthy food. Although the agronomic benefits of mungbean have been studied, best cultural practices and its impact on farming systems and soil fertility are scattered. The objectives of this research were to identify the best agronomic practices for mungbean production, assess its effects when grown together with millet, and measure its nitrogen contribution to the soil. The results showed that selecting the best genotypes to be grown in a particular soil texture can significantly increase mungbean growth and yield. In addition, incorporation of mungbean into cereal-based farming systems demonstrated its capacity for improving agricultural production in a low-input environment. Assessment of nitrogen fixation by mungbean showed that it can naturally add nitrogen into the soils, the most limiting plant nutrient, reducing nitrogen application needs. Thus, the ability of mungbean to diversify farming systems, improve soil fertility, and deliver nutritious food will provide agronomic, environmental, and economic benefits to farmers, especially in food-insecure households. However, exploitation of the full potential of mungbean won't be achieved without understanding the major factors influencing mungbean cultivation and production.

In general, the yields of alfalfa were increased by varying amounts of various fertility elements on the Norfolk sandy loam soil type at Williamsburg, Virginia. The yields of corn grown on the Hagerstown silt loam soil type at Blacksburg, Virginia, correspond closely to the fertilizer treatments and their availability. The milligrams of phosphorus absorbed by rye seedlings show no relation to the amounts of phosphorus added to the soil in fertilizers. In fact, in most trials the amount absorbed from treated plats was less than the amount produced from sand checks. It seems that all the phosphorus obtained came from the seed and not from the soil. From the studies reported herein, therefore, it must be concluded that the Neubauer seedling method is not applicable for determining the phosphorus requirements of the soil types used in this investigation. / M.S.

学位プログラム名: 京都大学大学院思修館 / 京都大学 / 新制・課程博士 / 博士(総合学術) / 甲第25517号 / 総総博第39号 / 新制||総総||7(附属図書館) / 京都大学大学院総合生存学館総合生存学専攻 / (主査)准教授 趙 亮, 教授 長山 浩章, 教授 関山 健 / 学位規則第4条第1項該当 / Doctor of Philosophy / Kyoto University / DGAM