Reduction in nitrogen fertilizer use results in increased rice yields and improved environmental protection

<p>Overuse of nitrogen fertilizer represents a considerable environmental problem globally, but especially in China. Recently, a recent approach on an experimental scale based on the diffusion of the so-called Three-Control Technology (TCT) successfully alleviated the overuse of nitrogen fertilizer in southern China villages in the Guangdong Province, serving as a reference point for other rice-producing countries tackling similar challenges. Here, we assessed the correlation between rice yields and reduction in the use of nitrogen fertilizer following the introduction of TCT. Our study was based on the collection of primary data from 248 households randomly selected from four rice-growing areas of Guangdong Province, China. Our results show that TCT significantly improved the efficiency in the use of nitrogen. Crucially, participating farmers, including both full adopters and partial adopters, were found to fundamentally change their application practices of nitrogen fertilizer, resulting in major improvements in the local soil and water systems.</p

Yield of farming practices (Y_f), attainable yield (Y_a), yield gap and the percentage of Y_f as Ya (Y_f /Y_a) for three rice faming systems.

<p>Note: yield gaps were estimated as differences between yields in farming practice on soils with various productivity levels and ‘attainable yields’, determined as mean yields of the 20% highest-yielding locations under BMPs. E-R, early rice, L-R, late rice, S-R, single rice. Solid and dashed lines indicate median and mean yields, respectively. The box boundaries indicate upper and lower quartiles, the whisker caps indicate 90th and 10th percentiles, and the circles indicate the 95th and 5th percentiles.</p

Relationships among management practices, soil inherent productivity and yield.

<p>Note: soil inherent productivity was estimated as yields in zero-N plots (Yield-N0). Black points represent farming practice (FPs); red points represent best management practice (BMPs). a, early rice (n = 98); b, late rice (n = 148); c, single rice (n = 157).</p

Relationships among management practices, soil inherent productivity and yield gap.

<p>Note: soil inherent productivity was estimated as yield in zero-N plots (Yield-N0). Yield gaps were estimated as differences between yields in farming practice on soils with various productivity levels and ‘attainable yields’, determined as mean yields of the 20% highest-yielding locations under BMPs. (a), early rice (n = 98); (b), late rice (n = 148); (c), single rice (n = 157).</p

Relationships among management practices, soil inherent productivity and N₂O emissions (a), CH₄ emissions (b), global warming potential (GWP, c), and greenhouse gas emission intensity (GHGI, d).

<p>Note: soil inherent productivity was estimated as yield in zero-N plots (Yield-N0). The GWP and GHGI is the sum of emissions of CO₂-eq of N₂O and CH₄ at area and yield scale during the rice growing season, respectively. Black points represent farming practice (FPs); red points represent best management practice (BMPs). For b, c and d, L-R, E-R and S-R represent late rice (n = 148), early rice (n = 98) and single rice (n = 157).</p