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In apple (Malus domestica Borkh.) orchards, rootstock genotype, and soil fertility management practices impact soil fertility, plant associated soil microbial communities, and orchard productivity. Apple growers select rootstocks to confer beneficial traits, including size control, precocity, and pest and disease resistance. Rootstock genotype may also influence microbial communities, resulting in changes that affect tree health and productivity. Many apple growers apply synthetic nitrogen fertilizers to improve fruit yield and quality. In excess of tree requirements, nitrogen fertilizers may reduce crop yield and quality, as well as contribute to water pollution. The addition of carbon-based amendments, such as yardwaste, chicken litter composts, and biochar, may potentially reduce nitrogen and water loss, while improving soil structure and mineral nutrient availability. Orchard and pot-in-pot experiments were designed to study the following objectives: 1) determine the effects of integrated carbon-based fertilizer amendments on tree growth, productivity, and orchard soil fertility, 2) assess the effects of biochar on tree growth, leaf mineral nutrition, soil physiochemistry, and microbial community structure and activity, and 3) understand how rootstocks and fertilizers alter soil microbial communities. Applications of composts, integrated compost-calcium nitrate fertilizers, and biochar increased soil carbon, organic matter, cation exchange capacity and microbial respiration. In the orchard study, nitrogen fertilizer application did not increase tree growth, fruit quality, or leaf nitrogen concentration. Biochar applied at high rates with nitrogen fertigation increased tree growth and leaf nitrogen concentration similar to nitrogen fertigation. In the pot-in-pot compost study, chicken litter compost increased tree growth, and integrated compost-calcium nitrate fertilizer applications increased leaf N concentration. Analysis of the microbial community structure of bulk soil samples from the biochar and compost pot-in-pot experiments determined that the community structure was similar for all treatments during the three-year study. Metagenomic sequencing of the rhizosphere bacterial community indicated that compost applications altered community diversity and evenness, and that compost treatments were more similar to each other than to the calcium nitrate treatment. Data from my dissertation research suggests that compost can be used to increase orchard soil fertility, tree growth, and leaf nutrition, and that compost applications increase soil microbial community diversity and activity. / Ph. D.

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Call number: LD2668 .T4 1978 K62 / Master of Science

Call number: LD2668 .T4 1979 F35 / Master of Science

Drip irrigation lines placed 15 cm deep or 5 cm shallow below soil surface and furrow irrigation were compared on calcareous soils of southern Arizona. Crops grown were zucchini squash (Cucurbita pepo L.) 1982 and 1983 summers, and cabbage (Brassica oleracea var. capitata L.), 1982 fall. Furrows received a preplant application of phosphorus (P) at a rate of 100 kg P₂O₅/ha. Urea phosphate (UP) (17-44-0) solution was injected twice in drip lines during the growing season to give a total rate of 100 kg P₂O₅/ha on cabbage and 50 kg P₂O₅/ha on squash. Deep drip lines produced 52 and 34% higher yield than shallow drip in squash 1982 and 1983 experiments respectively. Deep drip yields were comparable to fertilized furrow yields with half the water and half the fertilizer rate of the furrow used by the deep drip. Unfertilized furrow yielded least. Application of UP in deep drip raised PO₄-P and NO₃-N concentration in squash leaves to comparable values in fertilized furrow plants. Shallow drip and unfertilized furrow plants had low nutrient concentrations. Soil analysis for NaHCO₃ extractable P and NO₃-N showed higher levels under drip than furrow treatments. Available P increased to 20 cm from emitters. EC was lower under drip than furrow. Soil pH was reduced by 0.5 units around emitters. Soil moisture in root zone was highest under furrows. Deep drip had more moisture than shallow drip. Injection of UP reduced water pH to 1.8 which prevented P precipitation. Cabbage yields were comparable under all fertilized treatments. Deep drip yielded 19% higher than shallow drip. Tissue analysis showed higher nutrient concentration under drip than furrow treatments. Soil analysis showed higher available P and NO₃-N and lower EC and pH under drip than furrow treatments. Mobility of PO₄ from UP was about 20 cm in soil columns. Rate of P fixation was high. Reduction in pH followed same pattern of P mobility. Root growth and distribution was more extensive under deep than shallow drip. Roots concentrated around deep UP zone in transparent cylinders.

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No description available.

2 pp. / Plant growth regulators are commonly applied to wheat and barley grown under high-yielding conditions to reduce the risk of lodging. Plant growth regulators reduce lodging by reducing plant height and strengthening the stem.

Fertilizer plays a major role in the profitability of the farmer’s business, his/her future success as well as the sustainability of his business. Fertilizer is also one of the most expensive farm inputs, and therefore, has the ability to make or break the farmer. The emerging farmer market segment is expanding and holds a great deal of potential for fertilizer companies to supply the growing need of fertilizer in this market. Almost all fertilizer marketing strategies of South African companies have been designed to cater for the commercial farming sector; however, if fertilizer suppliers want to focus on the emerging farmer market segment, they need to understand buying behaviour of emerging farmers as well as their needs when developing strategies to utilize opportunities in this developing market. This study aims to do just that by identifying factors playing an important role in the buying behaviour of emerging farmers in the Free State when purchasing fertilizer. This study was conducted in two phases. During phase one, a literature review was conducted; phase two consisted of an empirical study. Questionnaires were used as a measuring instrument and were filled out by 32 participants to determine emerging farmer buying behaviour. Data was analysed by means of descriptive statistics and correlation analyses. The Coefficient of Cronbach’s Alpha was employed to verify the validity of the data. The results show that four (4) factors; (i) Service, (ii). Brand, (iii) Product and (iv). Learning/Psychological factors highly influence emerging farmers’ fertilizer purchase decision. The study also finally draws recommendations and conclusions for managerial perusal. / MBA, North-West University, Potchefstroom Campus, 2014