Using Nanoclay Polymer Composite for Efficient Delivery of N and P to Pearl Millet Grown in a Smectite Dominant Soil in a Green House Experiment

The hypothesis is that the exfoliated and dispersed nanoclay in the superabsorbent polymer matrix controls the rate of diffusion of ions/molecules out of absorbed water by the polymer matrix. The objective of the study was to assess the P and N release from fertilizer loaded nanoclay superabsorbent polymer composite (NCPC) and to test its potential as a carrier of slow release fertilizer in synchronization of plant's demand using pearl millet (Pennisetum glaucum) as a test crop. In general, availability of Olsen P, 0.01M CaCl2-extractable P and total mineral N in soils significantly enhanced on application of fertilizer loaded NCPC over conventional fertilizer (CF), at the same fertilizer dose. Further, nutrients availability in soils receiving low dose of fertilizer (LDF) as NCPC (NCPC-L) was statistically at par with that of high dose of fertilizer (HDF) as CF (CF-H), particularly at critical crop growth stages. At HDF, NCPC addition (NCPC-H) registered 65% additional biomass yield and 52 and 42% additional N and P uptake by pearl millet over CF (CF-H), respectively. Similarly, at LDF, biomass yield, N and P uptake increased to 59, 41 and 40%, respectively, under NCPC (NCPC-L) treated soils than that in CF (CF-L) treated soil. Different non-labile pools of inorganic P fractions increased significantly under CF application as compared to NCPC application, irrespective of fertilizer doses.