EFFECT OF JOJOBA AND CASTOR BEAN SEED RESIDUES AS SOIL AMENDMENTS ON SOME PHYSICAL AND HYDROPHYSICAL SOIL PROPERTIES.

Field experiments were carried out on silty clay loam soil at El-Gemmeiza Agricultural Research Station, El-Gharbia Governorate, during two consecutive growing seasons. Summer season 2007 and winter season 2007/2008 to evaluate the effect and residual effects of oil seed residues of jojoba and /or castor bean as soil amendments on improving some physical and hydrophysical soil properties. The rates of jojoba and castor bean seed residues were 0.0, 1.0 and 2.0 ton/fed. for each amendment which added before planting in the first season, while mineral fertilizers rates were 0.0, 0.5 and 1.0 of the recommended dose for each crop. The experiments were conducted in a split-split plot design with three replicates.
The obtained results can be summarized as follows :-
1- Soil penetration resistance decreased with all added treatments, also, by increasing the addition rates of these amendments, soil penetration resistance was decreased.
2-  The soil bulk density (Db) decreased in all treatments, while total soil porosity (E) and void ratio (e) take the opposite trend.
3- The settling percentage of the soil was decreased in all treatments, indicating a higher degree of structural stability.
4- The values of pore size distribution (large, medium and micro pores as a percent of total porosity) were significantly increased in the two growing  seasons.
5- Soil hydraulic conductivity (Kh) and soil moisture content, i.e., saturation percent (SP), field capacity (FC), wilting point (WP) available water (AW) and soil moisture content just before harvesting (θw) were significantly increased in all treatments in the two growing seasons.
6- Water consumption (Cu) was decreased and water use efficiency (WUE) was increased with all treatments of the two seasons.
7- From the above results, it is more useful to use those treatments (jojoba and / or castor bean seed residues) as soil amendments to markedly improve both physical and hydro physical properties under silty clay loam soils.