| Runoff rainwater harvesting and agroforestry are tools which offer solutions for problems of scarce water, food, fodder, and fuelwood in arid and semi-arid environments. The interrelationships of system components, such as trees and crops, and configuration, such as planting density, are not well understood in arid and semi-arid environments. The objectives of this research were to determine the effects of within row tree spacing, an intercrop, and tree green manure incorporation on harvested biomass yield. Nine microcatchment basins or limanim (pl.) were planted with Acacia saligna seedlings in an alley cropping configuration at the following three planting densities: 1, 2, or 3 m (2520, 1330, or 840 trees ha{dollar}sp{lcub}-1{rcub}{dollar}) spacing between seedlings within each row with 4 m spacing between rows. In a split-split plot design, half of each liman (s.) was planted with a Sorghum drummondii intercrop, and half again had A. saligna green manure incorporated into the soil. Three other limanim were planted with a S. drummondii monoculture. The limanim were flooded with 700 mm of water.; The results showed that while planting density did not significantly affect tree woody material yield, it did significantly affect tree foliage yield with the intermediate density yielding the most. There was no significant difference in intercrop production due to tree planting density. While statistically, there was no significant difference in intercrop production due to the presence or absence of trees, numerically there appears to be a difference which can be attributed to large sample variability. The addition of A. saligna green manure did not significantly affect tree foliage or wood yield or intercrop or monoculture production. The lack of a statistically significant effect of green manure on production might be viewed with caution as numerically production in the monoculture control appears to be greater than in the other monoculture treatments. This may be explained by both large sample variability inherent in this type of field experiment and perhaps by a relatively large C:N of the mature foliar material incorporated into the soil which may act to depress growth. For the most part, there was no significant difference in soil nutrient content in any of the plots due to green manure incorporation. The conclusions from this study are that in this particular setting agronomic yield is greatest in the intermediate density plots, however the decision for tree planting density, planting an intercrop, and incorporating green manure depends upon the farmer's needs and goals.; The findings of this research have implications for water management schemes evolving in the Middle East now that several players have signed peace treaties and agreements. With re-apportionment of water resources following peace, runoff agriculture and agroforestry are attractive options for water conservation and low water demand agricultural production in addition to fuelwood production where it is in limited supply. |
