Effect of straw and inhibitors on the fate of nitrogen applied to paddy soil

Abstract

A pot experiment was used to explore the distribution of fertilizer N and agronomic effects in a paddy soil-rice (Oryza sativa L.) system. Five treatments were set: without nitrogen, straw and inhibitor (C), urea (U), urea + straw (US), urea + urease + nitrification inhibitor (UI) and urea + urease + nitrification inhibitor + straw (UIS). Soil and urea-derived microbial biomass N increased significantly in US and UIS compared with straw-free treatments at seedling and tillering, indicating that biotic process play an important role in the retention of fertilizer N with straw addition. About 10% urea-N was recovered as fixed ammonium (FA) at seedling stage, subsequently released at tillering and maturation regardless of treatments, which emphasizes the importance of FA in the retention and supply of fertilizer N in paddy soils. Compared with U, rice yield and N uptake in US decreased by 7.8% and 25.2% respectively, while inhibitors (UIS) alleviated the reduction by 16.4% and 31.6%. The current research indicated UIS is recommended as the most appropriate management strategy in paddy soils of Northeast China based on N dynamics. But the economic effect as well as the field-scale validation need to be further evaluated.

Effects of Reduced N Application, Nitrification Inhibitor, and Straw Incorporation on Fertilizer-N Fates in Maize Cropping System: A Field ¹⁵N Tracer Study in Northeastern China

“…Similar findings were also obtained by Yuan et al and Cao et al, where straw incorporation enhanced fertilizer-derived N uptake by 15%-23% [9,40]. The newly immobilized N after C source addition, like a biological controlled-release fertilizer, can enhance native soil N availability, benefiting long-term crop N uptake [41]. The effect of organic additives on the fate of fertilizer-N depends on the activity of the organic material [42,43].…”

“…Straw incorporation can increase soil N availability because it accelerates the process of soil N mineralization and immobilization turnover (MIT). However, it may also decrease soil N availability because it fuels denitrifiers and increases N gaseous losses [39][40][41]. In this study, straw incorporation increased fertilizer-N retention in soil, promoted fertilizer-N uptake, and reduced fertilizer-N loss, although the difference was mostly insignificant.…”

“…In the presence of an activated C source such as glucose, negative ANI was usually observed because of the intense microbial immobilization, which reduced the crop N uptake derived from either fertilizer or indigenous soil [44][45][46]. In contrast, in the presence of an inert C source such as maize straw, its effect on fertilizer-N transformation would be much lower, mainly because of the slow degradation of straw materials [41,47] In addition to promoting the MIT and denitrification processes, straw returning also provides other essential nutrients (e.g., phosphorus, potassium) for crop growth [25,48]. Thus, straw returning is also considered an effective nutrient-conserving practice to increase nutrient supply capacity in the long term [49].…”

Effects of Combined Long-Term Straw Return and Nitrogen Fertilization on Wheat Productivity and Soil Properties in the Wheat-Maize-Soybean Rotation System in the Pannonian Plain

“…Straw return can promote root growth, reduce evaporation, increase soil water storage capacity, and create appropriate soil moisture conditions for crop growth, thereby increasing yield [11,22,[56][57][58]. However, if the amount of returned straw is too high, the relatively high C/N ratio can stimulate N absorption by microorganisms and reduce the amount of mineral N available for plant growth and development [59].…”

Effects of Corn Stalks and Urea on N2O Production from Corn Field Soil

“…The soil NH4 + -N and NO3 --N were extracted with 2 mol L −1 KCl solution [10], filtered, and analyzed with a continuous flow analyzer (AA3, Bran + Luebbe, Norderstedt, Germany). The extraction of soil 15 N-NH4 + -N and 15 N-NO3 --N was as described in Yu et al [25]. Soil 15 N-NH4 + -N and 15 N-NO3 --N content were determined by a Stable Isotope Ratio Mass Spectrometer (253 MAT, Termo Finnigan, Bremen, Germany).…”