Implementing sustainable nitrogen use in smal

Frontiers in sustainable food systems Publication of “mini-review” results of an examination of 46 peer-reviewed studies that compared a site-specific nutrient management (SSNM) approach to rice with farmers’ current fertilization practices. The scope of the study included research examples extracted from 11 countries conducted between 2001 and 2020 – using 43 studies from Asia and 3 from Africa.

SSNM Research strives to develop effective ways to apply nutrients that generate more efficient and profitable results, especially for smallholder farmers and their diverse agro-ecological landscapes. The concept grew out of work done over the past 30 years in the fragmented smallholder fields in Asia. Today SSNM is a globally recognized approach that is being extended across all levels of cultivation. SSNM’s research continues to evolve towards designing practical field solutions that offer proven alternatives to the once more common “one-size-fits-all” fertilization practices.

“The comparisons collected in this latest review clearly show that SSNM in rice crop systems increases rice yield, profits and nitrogen use efficiency while reducing nitrogen losses and greenhouse gas emissions when compared to farmers’ practices,” Summarize the authors.

The researchers found that the SSNM recommendations improved the average rice yield by 644 kg/ha (11.4%). SSNM also created a growing environment in which 38% of rice was produced per unit of N applied. This enhanced productivity translated into increased profitability, which is measured as an 8.6% increase in total returns over the cost of fertilizer.

These benefits are achieved when 14% less nitrogen fertilizer is applied compared to the farmers.

According to the study, SSNM achieved better results by more closely examining appropriate N application rates and how they should be balanced with other essential nutrients. Appropriate amounts of phosphorous and potassium are often used to improve the nitrogen absorption of rice. The authors note that most studies neglected micronutrients in their experimental designs. Going forward, the inclusion of micronutrients such as zinc and iron was encouraged in order to better quantify human nutritional benefits among those following rice-based diets.

Timing is just about everything

Farmers also lose yield and nutrient use efficiency by applying large amounts of nitrogen fertilizer in the early growth stages when rice plants have not fully developed the root system. Compared with farmers’ practices, the main impact of the SSN recommendations is the better distribution of nitrogen across the growing season, which often provides lower amounts of N. This prevents the accumulation of large pools of nitrogen in the soil, which is subject to various types of losses to the surrounding environment.

Despite this evidence, the impediment surrounding the widespread implementation of SSNM among smallholder rice farmers is the introduction of customized support systems that can ensure sustainable success. The ability to communicate SSN recommendations at scale through digital ICT solutions continues to improve.

The authors noted the challenge of working through the integration of the diverse range of social, economic, supply chain, and policy-making environments that smallholders face.

Successful implementation of SSNM on a large scale requires a pluralistic approach that fosters collaboration between multiple organizations and service providers with the support of governments.


The team of researchers involved in this study represents the Sustainable Impact Platform, International Rice Research Institute, Los Banos, Philippines; African Institute of Plant Nutrition, Experimental Farm at Mohammed VI Polytechnic University, Benguerir, Morocco; International Sustainable Impact Platform Rice Research Institute, New Delhi, India; and Analytical Services Laboratory, Department of Soil Science, Agricultural Systems Institute, College of Agriculture and Food Sciences, University of the Philippines, Los Banos, Philippines.

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