Nutrient removal by rice-wheat cropping system as influenced by crop establishment techniques and fertilization options in conjunction with microbial inoculation.

Nutrient uptake by the rice-wheat cropping system (RWCS) is an important indicator of soil fertility and plant nutrient status. The hypothesis of this investigation was that the rate and sources of nutrient application can differentially influence nutrient removal and soil nutrient status in different crop establishment techniques (CETs). Cropping system yield was on par in all the CETs evaluated, however, there were significant changes in soil nutrient availability and microbiological aspects. The system nitrogen (N), phosphorus (P), potassium (K) and zinc (Zn) uptake in aerobic rice system followed by zero tillage wheat (ARS-ZTW) was 15.7-17.6 kg ha-1, 0.7-0.9 kg ha-1, 7-9.8 kg ha-1 and 13.5-23.1 g ha-1 and higher than other CETs. The formulations of Anabaena sp. (CR1) + Providencia sp. (PR3) consortium (MC1) and Anabaena-Pseudomonas biofilm (MC2) recorded significantly higher values of soil chlorophyll and microbial biomass carbon and positively affected cropping system nutrient uptake and soil nutrient balance, illustrating the beneficial effect of microbial inoculation through increased supply of biologically fixed N and solubilised P. Zinc fertilization (5 kg Zn ha-1 through ZnSO4·7H2O as soil application) increased soil DTPA-extractable Zn by 4.025-4.836 g ha-1, with enhancement to the tune of 20-24% after two cropping cycles of RWCS. Our investigation recommends the need for change in the present CETs to ARS-ZTW, along with the use of microbial inoculation as a means of significantly enhancing cropping system nutrient uptake and soil nutrient status improvement.

Improving Water and Nutrient Use Efficiency in Rice by Changing Crop Establishment Methods, Application of Microbial Inoculations, and Zn Fertilization.

A field experiment was conducted during the wet seasons of 2013 and 2014 to evaluate the effect of three rice establishment methods: viz. puddled transplanted rice (PTR), system of rice intensification (SRI) and aerobic rice system (ARS), two cyanobacteria based inoculants, viz. Anabaena sp (CR1) + Providencia sp (PR3) consortium and Anabaena-Pseudomonas (An-Ps) biofilm formulation, and zinc (Zn) fertilization on the rice yield, water productivity, and nutrient use efficiency. The yields of rough, brown and milled rice were highest in SRI, which was on par with PTR and both methods proved significantly superior to ARS in both years. The total water productivity of rough and brown rice in the first year was significantly higher in SRI. The SRI method saved 21.9% and 27.4% irrigation water over PTR, and savings in ARS were 37.4% and 50.8% in first and second year respectively, over PTR. The use of An-Ps biofilm formulation along with 75% RDN improved the agronomic use efficiency of both nitrogenous and phosphatic fertilizers applied. On the basis of the present study, it can be concluded that SRI improved rice yields and water productivity; while involvement of An-Ps biofilm formulation can be recommended for improved nutrient use efficiency.