Benefits of the Forage Systems
Benefits to Soil
Studies conducted by Mureithi (1992) showed that intercropping Clitoria with Napier grass increased the N level in the soil (Table 5), possibly increasing the availability of N to Napier grass. Clitoria sheds its leaves throughout its growth but more so during the dry season (Njunie et al. 1995). Decomposition of Clitoria is likely to increase the soil N supply. On the other hand, the presence of Leucaena hedgerows significantly depressed P and K levels in the soil. However, this depression did not seem to affect the performance of Napier grass. A soil moisture study conducted to assess moisture extraction in the alley system by trees and Napier grass revealed that the soil below the Leucaena hedgerows had higher moisture content at all depths up to 2 m than the soil away from the hedgerows (Mureithi 1992). This was attributed to the harvest of rainfall by the trees and the ability of their root systems to extract soil moisture from deeper soil layers. This moisture could have boosted the growth of Napier grass rows adjacent to the hedgerows. Field observations also suggest that, when planted across slopes, the trees are very efficient in soil erosion control.
The Ministry of Agriculture has recommended Napier grass for establishing grass strips and stabilizing terrace banks. Also, most farmers planted these forages in parts of their farms requiring soil erosion control.