Farmers' fertilizer use gaps relative to government recommendations in the saline coastal zone of the Ganges Delta.

Overuse or underuse of nutrients relative to recommendations is a likely cause of crop yield gaps and an impediment to the achievement of food security. Government-endorsed recommendations are developed to deliver the best evidence-based advice on balanced fertilizer; however, deviations of farmers' nutrient use from the recommendations are rarely examined. This study chose the salt-affected coastal zone of the Ganges Delta, where low crop productivity and cropping intensity by smallholders limit their income, to determine current nutrient use gaps for the first time of three cropping patterns in two representative districts of Bangladesh. A total of 246 farms were surveyed from three farm sizes. Farmers' nutrient use gaps were compared with Fertilizer Recommendation Guides published in 2012 (FRG-2012) and 2018 (FRG-2018). Relative to FRG-2012 recommendations, farmers used 12%, 70%, and 11% overdoses of N, P, and K, respectively, under two fully rice-based cropping patterns, but the level of overdoses increased with farm size. Rates of K (14%), S (28%), and Zn use were below the FRG-2012 recommendations, especially for the smallest category of farms. However, the FRG-2018, increased recommended N (5%), K (62%), S (12%), and Zn rates but reduced P (25%) rates for fully rice-based cropping patterns. In contrast with rice, regardless of farm size, farmers applied overdose nutrients to watermelon but compensated with underdoses in the subsequent monsoon rice implying that farmers prioritized fertilizer expenditure on the most profitable crop. For the cropping pattern with watermelon, farmers could reduce the use of N (69%) and P (46%) and increase the use of K (48%), S (5%), and B. Reducing NPK use gaps can save treasury for both the farmers and the governments by 39.1 and 73.8 USD ha-1, respectively, under fully rice-based cropping patterns. Finally, our findings suggest there is scope to promote crop yields and sustainable intensification through balanced fertilizer use in a vulnerable saline region. Supplementary Information: The online version contains supplementary material available at 10.1007/s13593-022-00797-1.

Fertilizer use gaps of women-headed households under diverse rice-based cropping patterns: Survey-based evidence from the Eastern Gangetic Plain, South Asia.

Women-headed households (WHHs) have limited access to agricultural inputs and extension services relative to male-headed households (MHHs) which may lead to yield gaps, poorer livelihoods and greater food insecurity. Since lower fertilizer use by WHHs will restrict crop yield, we examined how limited access to fertilizer inputs and extension services was reflected in nutrient use gaps relative to Government recommendations. A total of 80 WHHs were randomly selected for interview from four Agro-ecological Zones (AEZs) covering five representative districts of Bangladesh to assess, for the first time, nutrient use gaps of WHHs under five rice-based cropping patterns. Data collected from 576 MHHs (reported elsewhere) was also utilized to examine nutrient use gaps, crop yields and farm income between MHHs and WHHs. The nutrient use rates were compared with the government Fertilizer Recommendation Guides (FRG): FRG-2012 and FRG-2018. The WHHs underuse N, P, K, S and Zn under fully rice-based cropping patterns, while MHHs overuse those nutrients, but WHH tend to overuse N, P, and K for patterns with potato and watermelon crops. WHHs seem to prioritize high-value crops for fertilizer use, but even yield was 14%, 11%, 17% and 15% lower for irrigated rice, maize, potato and watermelon, respectively compared to smallholder MHHs under diverse rice-based cropping patterns. Overall, WHHs had 10% and 14% lower farm incomes than MHHs under fully rice-based and high-value cropping patterns, respectively. Financial losses for both WHHs and the government due to overuse of NPK on high-value potato crops were estimated at around 63 and 115 USD ha-1, respectively. However, the socio-demographic information suggested that effective extension services targeted to WHH, easing of social restrictions on their mobility, access of WHHs to fertilizers at Govt. fixed price and improved financial capability through better credit access could bring WHHs towards balanced fertilizer use practices in the EGP.

Unbalanced fertilizer use in the Eastern Gangetic Plain: The influence of Government recommendations, fertilizer type, farm size and cropping patterns.

Intensive cropping systems with diverse cropping patterns present a challenge for nutrient management on smallholder farms. Government-endorsed recommendations for crop fertilizer use are designed to assist farmers achieve profitable and balanced nutrient inputs, but it is unclear how closely farmers follow these recommendations. We identified farmers' current nutrient use gaps (overuse or underuse) relative to the Government-endorsed recommended nutrient doses in two cropping patterns in three representative Agro-ecological Zones of Bangladesh. A total of 330 farms were surveyed in 2019 from three farm size categories (referred to as large-, medium and small-scale) and their gaps in nutrient use were assessed relative to Government-endorsed Fertilizer Recommendation Guides (FRG) published in 2012 and in 2018: FRG-2012 and FRG-2018. The large- and medium-scale farms used 11-16%, 80-90% and 21-30%, respectively, over-doses of NPK in the cropping season under fully rice-based cropping pattern relative to FRG-2012 recommendations, while the over-dose levels were much lower for small-scale farms. Small-scale farms used much less than recommended S, Mg, Zn, B and organic manure (OM) rates relative to FRG-2012. The FRG-2018, which increased N and K recommendations but decreased the P recommendation for rice crops relative to FRG-2012, shows that all farms can decrease the dose of P (by 50%) while small-scale farms need to increase the dose of N (7%), K (16%), S (20%) and to apply Zn in the fully rice-based cropping pattern. On the other hand, the farms could greatly reduce NPK (19%, 86% and 44%, respectively) use while increasing S (14%), Mg, Zn, B and OM use relative to FRG-2018 in the pattern with the high-value potato crop. To increase crop profitability, enhance food security and save Government treasury in the Eastern Gangetic Plain enabling approaches are needed to effectively communicate the benefits of balanced nutrient use practices to farmers.