Department of Plant Sciences

Productivity of coarse textured sandy soil is relatively low due to its extreme permeability which permits deep percolation of water and nutrients. Onattukara sandy tract is a fluvial and marine sand area of Alappuzha and Kollam districts of Kerala state in India which covers about 72550 ha. The cropping system practiced here is Rice-Rice-Sesame. Because of their low water holding capacity and high susceptibility to leaching of mobile nutrients, crops grown in these soils are more prone to water and nutrient stresses leading to low crop yields. For such soils reduction of seepage losses by reducing the relative proportion of macro pores through compaction has an important beneficial effect on growth and yield of rice (Oryza sativa) and Sesame (Sesamum indicum). Along with compaction, application of farm yard manure, coir pith and kayal silt will definitely improve soil physical properties such as water holding capacity, nutrient retention and soil structure. In order to alleviate the physical constraints of sandy soil and to enhance the nutrient and water use efficiencies, soil compaction along with the addition of farm yard manure, coir pith (waste material from coconut husk)and kayal silt( lake sediments) were tried to develop a new technology.

The field experiment is been conducted in a rice-rice-Sesame cropping system for three consecutive years at the Rice Research Station, Kayamkulam, and Kerala. The soil in this tract is sandy kaolinitic isohyperthermic psammaquent, highly permeable leading to high loss of nutrients and water. Design of the experiment was Factorial Randomized Block Design. The treatments consisted of the following factors-C0-No compaction;C1-Compaction with 400kg roller passing 4 times;F0-No farm yard manure;F1-2.5 t FYM;F2-5t FYM ha-1;S0-No kayal silt;S1-5 t ha-1Kayal silt;P0-No coir pith;P1-5 t ha-1coir pith(sieved).There are 18 treatments consisting of combinations of all the above factors excluding the combinations of S1 and P1 with other factors. After harvest of each crop soil physical properties, chemical properties, yield of crop and uptake of nutrients were analyzed using standard procedures. The first crop (rice), second crop (rice) and third crop (Sesame) recorded higher yield in compacted treatments when compared to non-compacted treatments. Compacting the soil of Onattukara sandy tract using 400kg roller passing 4 times at Procter moisture level with farmyard manure, coir pith and kayal silt has resulted in improvement of physical fertility of the soil. In the first crop rice the highest yield (3.15tha-1) was recorded by C1F1S0P1 (compaction+2.5t FYM+5t coir pith) treatment where as the same treatment without compaction gave only 1.60 t ha-1only half of the former.C0F0S0P0 treatment recorded a hydraulic conductivity of 6.86 cm/hr where as the same treatment with compaction reduced hydraulic conductivity to about half (3.24 cm/hr).The total uptake of N, P and K was increased significantly in compacted plots. The treatment C1F1S0P1 recorded lowest hydraulic conductivity in surface and sub surface layers and highest nutrient uptake. The yield increase in this treatment was due to reduction in leaching loss of nutrients by lowering the hydraulic conductivity and thereby increased uptake of nutrients. In second crop rice, the highest grain yield and straw yield was noticed in the C1F2S0P1 treatment. Highest root volume, leaf area index and N, P, K uptake were recorded by this treatment. Lowest hydraulic conductivity was also registered by this treatment. All these factors contributed for obtaining maximum yield in this treatment. Soil physical properties like bulk density, soil strength, mean weight diameter, micro porosity, water holding capacity and field moisture content were increased in compacted plots. Addition of FYM and coir pith enhanced the structural and moisture retention properties of soil. Compaction of coarse textured soils using 400 kg roller passing 4 times along with 5t ha-1 FYM and 5t ha-1 coir pith improved the soil physical properties, nutrient uptake and in turn yield of crops under rice based cropping system.