Effect o f some soil moisture conservation practices on soil moisture regime during field establishment o fb la ck pepper {Piper nigrum) in mid country sloping lands of Sri Lanka

Abstract

The high degree of plant mortality and slow growth rate are major problems during the establishment phase of black pepper and other perennial crops in the degraded sloping Sands of mid country in Sri Lanka. Therefore, several soil water conservation practices adopted in pepper cultivation on a sloping land were compared in terms of soil water balance. Soil moisture regime was monitored using a neutron probe during May 1992 to December 1993 at Matale (70 30’ N, 80 07’ E and altitude 357m above MSL). The soil moisture content values have been maintained above the permanent wilting point at 30cm beneath the coconut husk mulch placed on the reverse slope basins during both the first and second inter-monsoonal dry spells following the field planting. Surface run-off component was very Sow though the steepness was greater than 30%. Even though, the total field water balance for the whole period was positive, weekly balance showed a few weeks with negative balance, especially during February, March and mid September. Total profile soil water content reached the Permanent Wilting Point (21.7 vol %) level during such dry spells. Pattern of soil moisture regime revealed that the first inter-monsoonal dry spell i.e. February-Mareh is more severe than the second inter-monsoonal dry spell i.e. August-September for this location. Results suggest that the application of coconut husk mulch in association with run-off concentration basins around plants are beneficial for the successful field establishment of pepper. Furthermore, field planting of pepper on sloping lands in the mid country of Sri Lanka is more appropriate during the early half of south western monsoona! rains, when the soil profile is fully replenished.