Web-based tool for calculating field-specific nutrient management for rice in India

Abstract

Site-specific nutrient management (SSNM) can be an alternative to a recommendation for uniform fertilizer use across a rice (Oryza sativa L.) production system within a country or region of a country. We developed a web-based decision support tool named Nutrient Manager for Rice (NMR), which used principles of SSNM to calculate fertilizer N, P, and K rates for individual fields based on a target yield set for each field. It also used expected growth duration of the rice variety, crop establishment method, and age of transplanted seedlings to calculate days after rice establishment for each of three applications of fertilizer N. NMR enabled P rates to match estimated removal of P with harvested grain and crop residue for the target yield set for each field. We compared field-specific fertilizer recommendations from NMR with uniform application of fertilizer provided by an existing blanket fertilizer recommendation for irrigated inbred rice (BFR) and farmer's fertilizer practices (FFP) in on-farm trials conducted in 74 irrigated rice fields across three growing seasons in the Cauvery Delta, Tamil Nadu, India. Grain yield was 0.6-0.7 Mg ha -1 higher (P B 0.05) with NMR than FFP in two of the three seasons, even though total fertilizer cost was comparable or less with NMR. Yield was comparable for NMR and BFR, but NMR reduced fertilizer N and P rates and total fertilizer cost compared to BFR. Use of NMR rather than BFR also had less risk of financial loss for a farmer. The likelihood of financial loss with a switch from FFP to BFR averaged 31%. It reduced to 18% with a switch from FFP to NMR. NMR facilitated the calculation of field-specific fertilizer N, P, and K management practices, which increased fertilizer use efficiency without loss in rice yield compared to a recommended uniform fertilizer management across fields.

Importance of phosphorus and potassium in soil-specific nutrient management for wet-season rice in Cambodia

“…The sand content was negatively correlated with the clay content, CEC, and available K ( Figure 1); that is, a high sand content decreased the soil's ability to retain nutrients. Our finding that rice yield in the unfertilized plots strongly reflected the inherent soil fertility or nutrient-holding capacity agrees with previous studies (Homma et al, 2003;Sharma et al, 2019). As White et al (2000) suggested, the Toul Samroung soil proved to be the most fertile of the three soil groups used in this study, probably because of its high clay and CEC.…”

“…This would lead to a significant K deficit when adequate N and P inputs were provided. The soil nutrient status determined by basic soil analysis such as that in the present study may not always be associated with the rice yield (Banayo et al, 2018a;Sharma et al, 2019) because simple estimates of plant-available nutrient contents cannot always predict their relationship with plant nutrient uptakes (Dobermann and Fairhurst, 2000). Our results support those in previous studies of soil-specific nutrient management for Cambodian rice, but clearly suggest that there is an opportunity for upgrade.…”

“…Since there is growing evidence that the response of crop yield to management depends on the local growth environment, agricultural guidelines have become increasingly site-specific (Carberry et al, 2013). A well-known example is the development of site-specific nutrient management for tropical rice (Sharma et al, 2019). The recommendations for rice were based on a large dataset from nutrient omission trials in the target regions and accounted for the relationship between nutrient supply and crop demand in each field (Dobermann and Fairhurst, 2000).…”

Field-specific nutrient management using Rice Crop Manager decision support tool in Odisha, India

“…It was unique for each field trial and served as the RCM treatment. RCM typically set the target yield higher than the historical yield reported by the farmer during the RCM interview, but RCM also adjusted target yield downward when transplanting was delayed beyond a critical date, and RCM limited upward adjustment in yield for low-yielding rice varieties (Sharma et al, 2019). As a result, target yield was less than historical yield reported by the farmer in 12% of the field trials in our study.…”

“…Field-specific fertilizer recommendations calculated by NMR increased yield and net income compared to the existing farmers’ fertilizer practice in on-farm research with irrigated rice in southern India (Sharma et al, 2019). Sharma et al (2019) also compared NMR to an existing recommendation for a blanket application of fertilizer in the absence of soil testing. NMR recommendations did not increase yield compared to the blanket fertilizer recommendation (BFR), but NMR reduced fertilizer cost and risk of financial loss and increased fertilizer use efficiency compared to BFR.…”