Biomass Estimation and Spatial Distribution of Maize Root in China.

Abstract

Understanding the magnitude, spatial, and vertical distribution of agronomic crop roots and the driving factors are critical to estimate the share of cropland in C sequestration thus their role in mitigation of global warming. Here we compiled root data from 311 published references and 16 research trials conducted between 1986-2012, to analyze the spatial and vertical distribution of maize (Zea mays L.) root biomass (RB) and its associated C deposition in soil across China. The results showed that maize RB was 30.10 g plant^-1 or 0.18 kg m^-2, average across China. Carbon deposition into the soil associated with maize RB was estimated as 22.9 Tg yr^-1, 83% of which was found in the upper 30 cm layer of the soil. The mean of D₅₀ and D₉₅ (soil depths containing 50% and 95% of root biomass, respectively) was 11.3 and 94.3 cm. The Partial Least-Squares Regression models incorporating climatic, edaphic, topographical, and agronomic factors explained 42.4% and 56.7% of the variation in RB and root depth (RD), respectively. Agronomic management (especially planting density) was the dominant factor affecting RB, whereas RD was mostly influenced by soil-related factors (especially the proportion of sand and soil pH). These information are useful in estimating the share of croplands on the global C balance which has not received sufficient attention yet. Moreover, this information could be very useful in understanding soil process, and developing of ecosystem modeling, as well as in the estimation of cropland shares in the global C depository.