Synchronizing N Supply from Soil and Fertilizer and N Demand of Winter Wheat by an Improved Nmin Method

Abstract

Excessive nitrogen (N) fertilizer application and poor timing of N fertilizer application to winter wheat are common problems on the North China Plain. To study the possibilities of optimizing the timing and rate of N application, a field experiment was conducted from 1999 to 2001 in a suburb of Beijing. A control (no nitrogen) and two N fertilization strategies (conventional N application and optimized N fertilization) were designed to compare their effects on wheat growth, N nutrient status, grain yield and N balance. The conventional N fertilization strategy was given a fixed N rate of 300 kg N ha À1 , which was split, half in autumn and half in spring as a top-dressing. The timing and rate of N and application of the optimized N fertilization strategy were determined by the target value of soil mineral nitrogen demand for three growth periods of wheat, which is related to the target yield, and soil mineral N (N min ) in the effective rooting depth at the beginning of these three periods. Based on the optimized N fertilization strategy, a total of 55 and 65 kg N ha À1 had to be applied to winter wheat in the re-greening and shooting stages of the first and second experimental years, respectively. Compared with the high N rate before sowing in the conventional N fertilization treatment, the optimized N fertilization treatment did not require any N fertilizer before sowing of wheat. Despite a much lower N fertilization rate, no significant difference in N nutrient status, growth during the wheat growing period or grain yield was observed between optimized N and conventional N fertilization treatments. As a consequence of optimizing the rate and timing of the N fertilizer application to match wheat demand, a much lower residual N min and calculated apparent N loss was found as compared to the conventional N treatment. N recovery for the optimized N fertilization treatment (67% in 1999/2000 and 66% in 2000/2001) was much higher than that of the conventional N fertilization treatment (19% in 1999/2000 and 18% in 2000/2001). In conclusion, the optimized N fertilization strategy can synchronize N demand of wheat and the N supply from soil and fertilizer, and therefore drastically reduce N application rates without any yield losses.

Manure and sorbent fertilisers increase on-going nutrient availability relative to conventional fertilisers

“…Development of fertiliser products capable of precise in-season nutrient supply (Chen et al, 2006 holds the promise of improving nutrient use efficiency and greater yields without increasing fertiliser use (Zhang et al, 2011). The ability to defer P supply demonstrated in the pot trial through the use of either SL or HT additions may be useful in achieving this goal, where crop uptake profiles often involve a greater nutrient requirement later in the season than at the beginning.…”

“…By managing N fertiliser in a manner that ensured non-limiting N supply with minimum excess (and minimum losses) through in-season root zone N management. Chen et al (2006Chen et al ( , 2010 were able to almost double maize yields with no increase in fertiliser use (Zhang et al, 2011). In this management, total fertiliser N additions are divided into sub-applications that are applied throughout the growing season .…”

Long-term reduction of nitrogen fertilizer use through knowledge training in rice production in China

“…In 2006, China consumed 31 million tons of chemical nitrogen (N) fertilizer, accounting for about 32 percent of global N consumption (Heffer, 2009). Several studies have shown that in China, N-fertilizer use has been excessively used in grain production (Cai et al, 2002;Chen et al, 2006;Cui et al, 2008;Fan et al, 2007;Ma et al, 2008;Peng et al, 2002;Yan et al, 2012) and vegetable farming (Chen et al, 2004;He et al, 2009).…”

On-farm trials of optimal fertilizer recommendations for the maintenance of high seed yields in winter oilseed rape (Brassica napus L.) production

“…Several indices have been used to estimate soil N supply, such as alkaline hydrolyzable-N (Roberts et al 2011), nitrate (Cela et al 2013), soil mineral N (Chen et al 2006) and hydrolyzable amino sugar N (Khan et al 2001). Despite the fact that there are several indices, usage of each method has been limited, depending on numerous and complicated N-cycle processes.…”