Nitrogen rhizodeposition by legumes and its fate in agroecosystems: A field study and literature review

Abstract

Quantification of legume nitrogen (N) rhizodeposition (N derived from roots) and its fate in agroecosystems is crucial for managing soil fertility, land productivity, and agriculture sustainability. In contrast to forage legumes, the N rhizodeposition by grain legumes is nearly unknown. Therefore, N rhizodeposition of four grain legumes and its transfer to subsequent wheat crops was quantified using the 15 N stem labeling method under field conditions. The N rhizodeposition of the grain legumes: peanut, soybean, mungbean, and adzuki bean amounted to 25, 51, 20, and 63 kg N ha −1 , respectively. N rhizodeposition was not affected by fertilization, and it was 53-257% more accumulated in topsoil (0-20 cm) than that in subsoil (20-40 cm). However, N rhizodeposition per unit of root biomass in subsoil was 3.5-times as much as that in topsoil (p < 0.05), indicating the importance of legumes for soil fertility and exploration in subsoil. Remarkably, subsequent wheat utilized 13-85% of legume N rhizodeposition, which contributed to 4-20% of total wheat N uptake. Combining the present data with the literature review, the average N rhizodeposition of legumes (both grain and forage legumes) is 83 kg N ha −1 (n = 75), and one-fourth of which was utilized by subsequent cereals. Increasing root biomass by 1 g increases rhizodeposition by 53 mg N. In conclusion, legume N rhizodeposition is crucial for the sustainability of legume-based crop rotations resulting in soil N build-up and is an important N source for subsequent crops.

Evaluation of crop productivity, water and nitrogen use, and carbon footprint of summer peanut ‐ winter wheat cropping systems in the North China Plain

“…In addition, we found that PW increased the annual equivalent yield but decreased winter wheat yield in the first year. The introduction of legumes into the rotation system with cereals increased the subsequent cereal yields (Bundy et al, 1993; Preissel et al, 2015), which attributed to the N rhizodeposition from the legume (Wang et al, 2020b; Zang et al, 2018; Zhang et al, 2019). However, in our study, the available soil water before sowing is a key factor affecting the yield of winter wheat in the first year, due to a higher ET in the first summer season of PW, as soil water condition vastly affected the performance of winter wheat (Qin et al, 2018).…”

Soil Enzyme Activity and Stoichiometry: Linking Soil Microorganism Resource Requirement and Legume Carbon Rhizodeposition

“…Considered as important regulators of ecosystem processes, the functional traits of plants influence soil characteristics, soil resources dynamic and the abundance and diversity of microorganisms [92,93]. The differences observed between legumes and cereals are related to particular physiological functioning that allows them to fix atmospheric N 2 , to have N-rich tissues and to enrich the soil in N such as those reported in the literature [20,94,95]. For example, ACP activity in the soil is produced and released by both roots and microorganisms.…”

Simazine degradation in agroecosystems: Will it be affected by the type and amount of microplastic pollution?

“…In the same pot experiment, we observed that microplastics inhibited the growth of wheat (Zang et al, 2020). In turn, it could reduce rhizodeposition and as a consequence reduce the production of microbial enzymes due to a lack of energy resources (Wang et al, 2020; Zang et al, 2019). In line with this, PVC addition suppressed C‐degrading enzymes, whilst 1% and 20% of PE addition decreased N‐degrading enzymes, compared to the soil without microplastics ( p < 0.05, Figure 4).…”