Effects of Fertilizer Placement and Nitrogen Forms on Soil Nitrogen Diffusion and Migration of Red-Yellow Soil in China

Abstract

A better understanding of nitrogen (N) diffusion and transformation in soils could reveal the capacity of the biological inorganic N and improve the efficiency of N fertilizers. A field micro-plot experiment was carried out to study the effects of fertilization methods (mixed uniformly with 12 cm top soil, placed in holes at a 12-cm depth, or placed in furrows at a 12-cm depth) and forms of N fertilizers (urea and ammonium phosphate) on the dynamics of soil N's vertical diffusion and horizontal migration in red-yellow soil. The soil inorganic N ( was greater than that from mixed or furrow applications. Under point placement, the migration of soil inorganic N in urea and ammonium phosphate treatments occurred in the 6 -15 cm layer at a horizontal distance of 0 -9 cm. However, the nutrient preservation capability of the soil receiving ammonium phosphate was greater than that receiving urea under point deep placement. Thus, point deep placement had a tendency to increase the inorganic N in the soil and reduce inorganic N loss, which probably occurred due to the reduced soil volume with which the N fertilizer was mixed. According to crop growth and fertilizer requirements, the optimized fertilizer placement and N species resulted in a continuously high nutrient supply to crops for 90 d. However, the effects of point deep placement on increasing the N-use efficiency and reducing N loss have to be evaluated under natural field conditions.

Localized nitrogen supply facilitates rice yield and nitrogen use efficiency by enabling root-zone nitrogen distribution and root growth

“…This was because the contact area between N fertilizer and soil determined the dilution and rate of release of N fertilizer; the more extensive contact area results in higher dilution and rates of release of N fertilizer. The dilution and rate of release of N fertilizer were the smallest under RZF conditions, and less inorganic N was lost (Jiang et al, 2017).…”

Effects of local nitrogen supply and nitrogen fertilizer variety coupling on rice nitrogen transport and soil nitrogen balance in paddy fields

“…The contact area between N fertilizer and soil can be in the following order: broadcasting > strip application > cavity application. Therefore, it can be hypothesized that the N fertilizer dilution and release rate are the lowest under R, the N occurs due to leaching, and runoff losses are smaller (Jiang et al, 2017). Interestingly, Ju and Zhang (2003) argued that this residual N was not necessarily lost immediately and might also serve to replenish the soil N pool with good management (Ju and Zhang, 2003;Smith and Chalk, 2018).…”

“…Zhu et al (2019) reported that M promoted N uptake in rice by increasing soil ammonium-N concentration and further reducing N loss. Jiang et al (2017) showed through a field micro-plot experiment that the vertical migration distance of fertilizer-released N under the M was 3-18 cm, while the vertical migration distance under R was 6-15 cm in the soil layer, and the ammonium N content under R was 8.3 times higher than that under M. This indicates that R had a tendency to increase the inorganic N content of the soil and reduce the inorganic N loss. In addition, the higher nutrient concentration could provide sufficient N to seedlings after regreening, promote tillering, reduce ammonia volatilization by 26-93% (Liu et al, 2015;Wu M. et al, 2017), and also reduce N oxide emissions (Yao et al, 2017;Gaihre et al, 2018).…”

Characteristics of N Transformation of Humic Acid Urea in Different Circle Layers of the Fertisphere: A Simulated Experiment

“…The fertisphere is the primary space where urea granules participate in the soil nitrogen cycle [27]. Previous research demonstrated that the lateral migration distance of common urea at 90 days was approximately 5-7 cm, whereas vertical migration was primarily centered in the soil layer range of 6-18 cm [28]. Additionally, the nitrate nitrogen in the soil increases over time and with decreasing soil water content, while the ammonium nitrogen migration distance increases with both increasing soil water content and time [29].…”