Multi-Seasonal Nitrogen Recoveries from Crop Residue in Soil and Crop in a Temperate Agro-Ecosystem

Abstract

In conservation tillage systems, at least 30% of the soil surface was covered by crop residues which generally contain significant amounts of nitrogen (N). However, little is known about the multi-seasonal recoveries of the N derived from these crop residues in soil-crop systems, notably in northeastern China. In a temperate agro-ecosystem, 15N-labeled maize residue was applied to field surfaces in the 1st year (2009). From the 2nd to 4th year (2010-2012), one treatment halted the application of maize residue, whereas the soil in the second treatment was re-applied with unlabeled maize residue. Crop and soil samples were collected after each harvest, and their 15N enrichments were determined on an isotope ratio mass spectrometer to trace the allocation of N derived from the initially applied maize residue in the soil-crop systems. On average, 8.4% of the maize residue N was recovered in the soil-crop in the 1st year, and the vast majority (61.9%-91.9%) was recovered during subsequent years. Throughout the experiment, the cumulative recovery of the residue N in the crop increased gradually (18.2%-20.9%), but most of the residue N was retained in the soil, notably in the 0-10 cm soil layer. Compared to the single application, the sequential residue application significantly increased the recovery of the residue N in the soil profile (73.8% vs. 40.9%) and remarkably decreased the total and the initially applied residue derived mineral N along the soil profile. Our results suggested that the residue N was actively involved in N cycling, and its release and recovery in crop and soil profile were controlled by the decomposition process. Sequential residue application significantly enhanced the retention and stabilization of the initially applied residue N in the soil and retarded its translocation along the soil profile.

Contribution and fate of maize residue-15N and urea-15N as affected by N fertilization regime

“…If more mineral N is added at the beginning to narrow the C/N ratios, the immobilization of residue-N will be mitigated and hence the bioavailability of residue-N will be promoted. When crop residues with wide C/N ratios were incorporated into soil, a large range from 4% to 20% of the applied residue N was reportedly recovered by crops in the first growing season [14,29,34,55–56]. However, opposed findings showed that air and soil temperatures are the driving force for residue decomposition, rather than N addition [57].…”

“…China produces approximately 925 million tons of crop residues annually [11], with 34.2%, 33.1% and 14.5% of the total nutrient resources originating from maize, rice, and wheat residues, respectively [12]. Maize residue generally contains approximately 80 kg N ha –1 , which may act as an important N source for soil N pools and subsequent crop N uptake [13–14]. Winter wheat-summer maize rotation is the dominant crop system in the North China Plain, where Fluvo-aquic soils have poor soil fertility because of its calcareous nature, frequent tillage and lack of organic matter [8].…”

Comparing microbial transformation of maize residue‐N and fertilizer‐N in soil using amino sugar‐specific 15N analysis

“…From the second year, the accumulation of maize residue‐N in soil accelerated, and as a result, the N content derived from maize residue peaked in the third year (Figure ) when the initially applied maize residue was almost decomposed (Hu et al, ). Generally, the release of maize residue‐N into soil was limited by the enzymatic depolymerization of proteins (Burgess, Mehuys, & Madramootoo, ; Jones et al, ), of which protein‐N accounted for approximately half of maize residue‐N in our experiment (data not shown).…”

“…a 30% weight loss of the mulching maize residue and the significant fertilizer-N immobilization in the first year, only a very small amount of maize residue-N was initially released into soil, and accordingly, microbial assimilation of maize residue-N was restricted (Figures 1 and 2). This scenario occurred because the maize residue, which was spread on the soil surfaces, underwent slow decomposition (Hu et al, 2015;Lupwayi et al, 2006). The released components needed to be leached or bioturbated and then transported to the soil (Coppens, Garnier, Degryze, Merckx, & Recous, 2006).…”

Design of bionic locust mouthparts stubble cutting device

“…This planting mode can preventing soil erosion and improving soil organic contents and pore structures, and thus has become the major popularized agriculture method throughout China [4,5] . However, the stubble breaking operations before springtime planting are limited by heavy resistance and high power consumption, which largely complicate the production costs and severely restrict the popularization of this mode [6] . Thus, it is urgent to study the mechanism of resistance and consumption reduction during stubble cutting and design stubble breaking mechanisms for efficient cutting, which will significantly promote the stubble-returning agricultural mode and thereby improve the quality of cultivated lands.…”