EFFECT OF RAIN WATER HARVESTING AND DRIP IRRIGATION ON CROP PERFORMANCE IN AN ARID AND SEMI-ARID ENVIRONMENT

Abstract

Rainwater  harvesting  and  drip  irrigation  are  possible  interventions  to  enhance  crop performance in Arid and Semi-Arid Lands (ASAL). Work was undertaken to evaluate the feasibility of rainwater harvesting for bean production under an ASAL environment in Kaiti  Watershed,  Makueni  District,  Kenya.  Treatments  comprised  two  rainwaterharvesting  methods,  Zai  pits  and  contour  ridges;  bucket-kit  drip  irrigation  and  a control. No intervention was made to enhance water availability in the crop root zone in the control. The experiment was arranged in a Randomized Complete Block Design with  three  replicates.  Each  of  the  12  experimental  plots  was  planted  with  beans (Phaseolus vulgaris L.), variety GLP 2. Soil moisture content and pan evaporation were measured  daily  for  100  days  and  runoff  after  every  rainfall  event.  Crop  height  was measured once a week and grain and biomass yield were determined at the end of the growing  season.  Soil  moisture  content  and  crop  performance  were  significantly influenced  by  drip  irrigation  but  not  by  rainwater  harvesting.  In  drip  irrigated  plots, grain and biomass  yield, were 4 tonnes ha-1and 9 tonnes ha-1respectively compared to 3.5 tonnes ha-1and 7.5 tonnes ha-1respectively, in the control plots. Drip irrigation effectively  maintained  adequate  soil  moisture  resulting  in  better  crop  performance while  rain  water  harvesting  methods  failed  to  significantly  enhance  soil  moisture content and crop performance. This study indicated that rainwater harvesting makes a difference  in  runoff  when  the  14  Day  Antecedent  Precipitation  (14DAP)  exceeds  80 mm.  However,  the  grain  yield  obtained  in  all  the  plots  was  higher  than  the  national average of 0.36 tonnes Ha-1. It is recommended that further research be done under different  rainfall  conditions  to  confirm  the  conditions  under  which  the  benefits  of rainwater  harvesting  using  contour  ridges  and  zai  pits  can  be  realized  in  the enhancement of crop performance in ASAL conditions.