Date of Award

December 2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Division of Agriculture (SAFES)

Committee Member

Dara Park

Committee Member

William Bridges

Committee Member

David White

Committee Member

Alex Chow

Abstract

The results of Libyan agricultural review confirmed that soil degradation and limited freshwater resources are the primary causes of the country’s dependence on food imports. The intrusion of the seawater into the groundwater is causing soils to become salt-affected. In addition, many crops in the country are susceptible to pests. The spatial distribution of soil degradation occurrence and type were predicted using regression models, estimating that 666 882 km2 (53.5 %) of Libyan soils are degraded with 46.4 % due to salinization, 6.4 % water erosion and 0.66 % wind erosion.

The majority of the soils in Libya are sandy and have low water holding capacity. This situation is made more critical because of the low rainfall arid climate. Conducting research in Libya and obtaining Libyan soils is currently not possible. Soils in South Carolina are somewhat similar to those of Libya, having a sand-dominated surface horizon and root restriction subsurface horizon. In addition, SC has been experiencing intense mini-droughts during the primary growing season (summer). Thus, while not a perfect match, the information obtained from field and greenhouse experiments conducted in SC could be applied to Libya. Overall, minimal effect of soil conditioners on volumetric water content and plant growth and yield from the two field experimental research due to the excessive rainfall that that the fields received. Although little effect occurred due to soil conditioners, the pattern of positive response during two very wet seasons suggest that soil conditioners application during dry periods may have beneficial effects. The results from the two greenhouse experiments documented that soil conditioners can be as a soil management for increasing agriculture production in the field or greenhouse. The results from the third experiment documented that soil surfactant application with split water applications can reduce leachate resulting in conserving natural water resources. The results of nitrogen balance also suggested that the application of surfactants with fertilizer can be a management strategy for improving greenhouse substrates efficiency increasing uptake of N and reducing N leaching, thus improving the horticulture production. Most data suggested that soil conditioners can be used in droughty soils under limited water conditions as found in Libya as a management tool to improve the agriculture production in the country.

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