Effect of mulch and irrigation level on biomass, water use efficiency and nutrient uptake of forage maize in different textured soils

Two soil textures viz. loam and clay were used. These soils were air dried ground and passed through 2mm sieve thoroughly mixed and filled in earthen pots having thin plastic sheet placed inside @ 10 kg pot-1. A basal dose of NPK was added @ 150 ppm nitrogen, 100 ppm phosphorus and 50 ppm of potassium. Two mulch levels i.e. control (M0) and 6.7 Mg ha-1 (M1) of wheat straw were applied at the time of sowing. Crop water requirement was determined by Modified Penman Model. Then three irrigation levels, viz. I0 (100%), I1 (80%) and I2 (60% of total crop water requirement) were selected at 30mm water deficit. Hybrid maize variety R-2205 was sown @ 8 seed per pot. When the seed germinated, the seedling was thinned to four. Plant protection measure was carried out as and when needed. Plants were harvested twelve weeks after sowing and shoots and roots were collected and their fresh and dry weights were recorded. Shoot and root were also analyzed for N, P and K concentration. The data so collected was analyzed statistically following Completely Randomized Design in factorial arrangement. It was concluded that wheat straw mulch significantly affected growth of maize as it increased fresh weight of root, leaf area index and water use efficiency. 2. Soil texture affected significantly the oven dry weight of root, root/shoot ratio and leafs area index mostly in clayey soil. More growth of maize fodder was noticed in clayey soil than that in loamy soil. 3. Maximum plant growth was noted in case of sandy I0 100% CWR followed by I2 (60% CWR) and I1 (80% CWR) in most of the cases for all the growth parameters studied. 4. Interaction between mulch and soil texture was found statistically significant as increase in parameters like fresh weight of root, root/shoot ratio, leaf area index and potassium concentration in shoot and root was observed. 5. Interaction between wheat straw mulch and irrigation level was increased statistical l y in most of the cases. But interaction between soil texture with irrigation level and their combined effects were also affected significantly in some cases (e.g. oven dry weight of root, N and K concentration in shoot and root, N and P uptake in shoot). 6. Soil texture had no effect on N concentration and its uptake in root but N concentration and uptake in shoot significantly increase in clay than loam soil. Phosphorus concentration and uptake in root was significantly increased in clay, while its concentration and uptake in case of shoot increased in loamy soil. 7. There was statistically no effect of wheat straw mulch on nutrient concentration and their uptake. 8. A positive correlation was observed between water stress with crop on nitrogen concentration and their uptake, potassium concentration in shoot and phosphorus and potassium uptake in root. 9. Modified Penman Model was valid only up to one week after the establishment of the crop. As the crop grew further, its t r anspiration rate was very high and the soil water deficit increased beyond the 30mm deficit selected for this study. So the Penman Model under wire-house conditions failed badly. Thus the original irrigation levels were maintained for rest of the growth period.