Carbon Sequestration in Irrigated and Rain-Fed Cropping Systems Under Long-Term Fertilization Regimes
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ORIGINAL PAPER
Carbon Sequestration in Irrigated and Rain-Fed Cropping Systems Under Long-Term Fertilization Regimes Renjie Wang 1 & Jiangxiang Zhou 1 & Junyu Xie 2 & Asif Khan 1 & Xueyun Yang 1 & Benhua Sun 1 & Shulan Zhang 1 Received: 15 September 2019 / Accepted: 19 January 2020 # Sociedad Chilena de la Ciencia del Suelo 2020
Abstract It is important to understand soil organic carbon (SOC) sequestration and its relationship with crop productivity. Based on two long-term experiments under irrigated vs rain-fed conditions conducted in the China Loess Plateau, we evaluated SOC sequestration efficiency under diverse fertilization regimes and quantified the relationship between crop yield and SOC. The experiments consisted of a winter wheat-summer maize system under irrigated conditions with nine treatments—nitrogen (N), N and phosphorus (P), N and potassium (K), P and K (PK), combined NPK, crop straw (S) in combination with NPK (SNPK) and dairy manure (M) integrated with NPK (M1NPK and M2NPK)—and a winter wheat-summer fallow system under rain-fed conditions with seven treatments—CK, N, NK, PK, NP, NPK, and MNPK. After 25 years, the SOC storage was generally higher in the irrigated plots than in the rain-fed plots by 6% on average. The carbon sequestration efficiency was higher under the rain-fed (28%) than under the irrigated (19%) condition. The relationship between relative yield and SOC content suggested that the threshold SOC contents for obtaining the highest crop yield were 10.0 and 8.8 g kg−1 for the winter wheat-summer maize and winter wheat-summer fallow cropping systems, respectively. This difference suggests that a higher SOC level is required to support high crop productivity in the irrigated system than in the rain-fed system. Keywords Soil organic carbon . Carbon input . Carbon sequestration efficiency . Carbon sequestration rate
1 Introduction Increasing soil organic carbon (SOC) sequestration in cropland systems can decrease levels of atmospheric carbon dioxide, improve soil fertility (Lal 2004), and thus reduce variability in crop yield (Smith et al. 2007). SOC sequestration depends largely on the input of organic carbon (OC), which in most cases is from the return of crop residues and the addition of other exogenous organic supplements such as organic manure and compost. Among the organic supplements, crop
* Xueyun Yang [email protected]; [email protected] * Shulan Zhang [email protected] 1
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, Shaanxi, China
2
College of Natural Resources and Environment, Shanxi Agricultural University, Taigu 030801, Shanxi, China
residues are the most abundant and commonly used sources of OC. However, the quantity of crop residues varies greatly according to numerous studies. For example, analyzing the data from 17 long-term experimental sites in northern China, Zhang et al. (2016) reported that the OC
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