Impact of Intensive Greenhouse Production System on Soil Quality

Composite top- and subsoil samples were collected from the greenhouses in the Al-Balawneh area, Jordan, where intensive greenhouse production system (IGPS) has been practiced since 1998, to study the impact of IGPS on soil quality as measured by the chemical and biological properties to develop a sustainable production system. The study showed that IGPS led to higher electrical conductivity in top- and subsoils compared to an uncultivated soil (control). Quality and amount of irrigation water, lack of efficient drainage, and quantity and types of applied fertilizers were major factors resulting in salt buildup. IGPS resulted in lower total N (TN) and NO3-N in the soil compared to the control. The lower TN was due to crop uptake, microbial immobilization, volatilization, and irregular application of composted animal manure or poultry manure. In contrast, higher residual Olsen-P content was detected in both soil layers of greenhouses than in the control. Residual P was classified as very high in the topsoil layers and sufficient to high in the subsoil layers. Residual available K in the soils of greenhouses was relatively lower than that in the control and it was, however, classified as high to very high. A large increase of Cl and a considerable decrease in the bacterial count were observed in both soil layers of IGPS compared to the control treatment. Economically sustainable soil management practices need to be adopted by farmers to achieve a sustainable and profitable production. This can be accomplished through education, targeted towards the farming community in the central Jordan Valley.