Thesis (Ph. D.)--Brown University, 1990. / Vita. Includes bibliographical references.

Thesis (M.S.)--Purdue University, 1979. / Photocopy. 28 cm. Includes bibliographical references (leaves 201-207).

Thesis--Université de Kinshasa, 1989. / Includes bibliographical references (leaves 63-64).

Key factors in using variable renewable energy to sustain crop growth were investigated using the Isle of Lewis as a case study. Methods investigated sought to exploit plants' abilities to accommodate a variable solar input by supplementing it with variable renewable energy. The extant solar resource on Lewis was characterised. The mean ratio of photosynthetically active radiation (PAR) to solar radiation (SR) (fE) recorded in 2010 was 0.458. fE was found to be significantly different between the first and last hour of daylight and 12:00 GMT (F, (2, 33) = 7.98, p<0.001) and between winter and summer months (F, (1, 10) = 20.86, p<0.001). This supports the suggestion that fE decreases as the atmospheric path length decreases. Significantly higher mean fE was also identified for the cloudiest days (F, (1, 22) = 6.22, p<0.05). Supplementing sunlight with intermittent, artificial illumination powered using wind energy significantly increased the growth of Brassica hirta. 53.26% of the additional dry weight produced using fixed diurnal illumination was achieved with 35% of the energy using this technique. The dry weight of B. hirta grown with illumination timed with tidal streams was not significantly different from that grown using fixed diurnal patterns. This is potentially important for the use of renewable energy for horticultural illumination. The possibility of using energy to prioritise lighting in well insulated growing structures and the compatibility of electricity production and horticultural demand on Lewis were considered. These findings support the direct use of variable renewable energy to sustain crop growth and promote the concept of using plants to store renewable energy. This is of potential benefit for problems of renewable energy intermittency, the predicted need to increase world food supply and providing economic opportunities for remote areas with a poor solar resource but good supplies of variable renewable energy.

This study uses linear programming and econometric tools to determine the impact of agricultural productivity (technology) on agricultural exports. The study determines total factor productivity (TFP) using the Malmquist index method for a panel of 64 countries. Productivity impact on exports is determined by a two-stage estimation procedure. The results show agricultural productivity affects agricultural exports. This has important implications for developing countries. A 1 unit change in cumulative TFP increases agricultural output by .79% and a 1% increase in estimated agricultural output increases exports by .37%. Therefore, the total effect of technology on exports of primary and processed commodities is .29%. Developed countries generally have higher TFP rates, leading to higher export earnings; meanwhile, developing countries are not getting the benefits from agricultural exports because they have a relatively lower level of agricultural productivity. Investing in research and development for agriculture can improve technology, which, in turn, can Increase agricultural exports.

No description available.

<p> This thesis provides a means of measuring the type and number of livestock on a given farm in southern Ontario using as a data base aerial photographs of medium scale. The feasibility of making such measurements is shown to be an extension of past work in the field of agricultural air photo interpretation. The methodology is presented in the form of a model. The inputs from aerial photographs are crop acreages, building type and dimensions, and silo sizes. Average yields in each study area, in combination with crop acreage gives feed available. A comparison is made between feed weight and housing space available and required feed weights and stabling facilities (taken as constants in southern Ontario) to support cattle of a given type. This comparison technique, within the model, yields an output of farm type and actual numbers of cattle. The accuracy of prediction so obtained is high and is independent of the location or attributes of the widely spaced sample areas.</p> / Thesis / Master of Arts (MA)

No description available.

An average slope index and a number of agricultural productivity indices were determined for a sample of 100 districts in Costa Rica. To establish the relationship between these variables, correlation coefficients were calculated between the average slope index, on the one hand and, on the other, total gross agricultural income, total net agricultural income and also income and yields for individual crops. These relationships were calculated for the meseta central (the central, highly-populated area) and for areas outside of the meseta central and for the total sample taken from all of Costa Rica. Cases in which gross agricultural incomes were much lower than predicted by the study were investigated further to identify other factors which may have influenced the results. / Thesis / Master of Arts (MA)

No description available.