EFFECTS OF HYDROGELS ON SOIL MOISTURE, NUTRIENTS AND GROWTH OF SOME AGROFORESTRY TREES IN WEST POKOT COUNTY, KENYA

Abstract

Studies on the effects of hydrogels on soil amendments, moisture conservation, nutrients release, availability and growth of Sesbania sesban, Cajanus cajan and Leucaena pallida in arid and semi-arid lands (ASALs) was carried out. Hydrogels are hydrophilic in nature and highly absorbent to water molecules. This property helps to establish seedlings in ASALs. The effects of hydrogels on the growth of seedlings, nutrients and amount of moisture released have not yet studied and documented. The study was carried out in Kongelai in West Pokot County. Seedlings of S. sesban, C. cajan and L. pallida were established both in the nursery and in the field with and without hydrogels. Field experiment was carried out in split plot design under hedgerow intercropping system with three replications and three concentration hydrogels levels (7g, 11g and 15g) and control seedlings established in soils without hydrogels. In the nursery, root collar diameter and heights for each seedlings were measured every two weeks upto eight weeks. Seedlings established without hydrogels in the nursery were transplanted into field soils with none, 7g, 11g and 15g level of hydrogels. Root collar diameter and height were again measured every month for three months. In addition, soil was collected randomly once every month from the base of each seedling and analyzed for soil moisture and nutrient content using standard laboratory procedures. All data were subjected to analysis of variance using Analysis Toolpak. Results show that there was a significant difference in the height and RCD among the three species and at different level of hydrogels F calculated (0.05) = 10.3431 > F tabular (critical) 3.4903. This suggests that use of hydrogels in the nursery soils retards plant growth but improves growth in the field. Hydrogels increased soil moisture volume from 5.7, 8.3 and 5.3% to 11.7, 13 and 10% in H15g level of hydrogels in S. sesban, C. cajan and L. pallida respectively after transplanting. Analysis of variance of nutrients release into the soil shows that F calculated (0.05) = 5.4270 > F tabular (critical) 2.9011 implying that hydrogels has an effect on the nutrients. Nutrient increased from 0.95, 0.07 and 0.12% in the pre-test analysis to 4.48, 3.81 and 0.42% after analysis in potassium, nitrogen and phosphorus respectively in the soil after transplanting. It was concluded that hydrogels does not contribute to growth of seedlings in the nursery but it does so after transplanting. Hydrogels increase soil moisture and nutrients in the soil therefore recommended for use in semi arid lands to boost the survival and growth of seedlings. Hydrogels level at 15g is highly recommended to be used in the transplanted seedlings in ASALs