国家重点研发计划项目（2017YFD0300707）和国家自然科学基金项目（41571280, 41101276, 41907005）资助
Shenyang Agricultural University
Supported by the National Key Research and Development Program (No. 2017YFD0300707) and the National Natural Science Foundation of China (Nos. 41571280, 41101276, 41907005)
颗粒有机质是土壤活性有机质的重要组成部分，是评估土壤有机质变化的敏感指标。东北地区气候寒冷，稻田土壤淹水期短，非淹水期长且多处于冻结状态，水稻秸秆碳氮在黑土不同种稻年限土壤颗粒有机质中的分配如何尚不清楚。通过室内培养试验，将1%双标记（13C/15N）水稻秸秆添加到不同种稻年限（0、12、35、62和85 a）土壤，淹水培养150 d（培养温度20 ℃，淹水层1 cm），去除淹水层后冻结培养150 d（培养温度-15 ℃，饱和水分状态），研究水稻秸秆碳（氮）在不同种稻年限土壤颗粒有机碳（Particulate organic carbon, POC）和颗粒有机氮（Particulate organic nitrogen, PON）中的分配特征。结果表明，在培养过程中，未添加和添加水稻秸秆处理，各年限稻田土壤POC和PON含量均低于对照土壤（0 a），添加秸秆处理的各年限土壤POC和PON含量在淹水培养5 d时明显增加，但其后并未表现出一致的增加趋势。秸秆碳（氮）对各年限土壤POC（PON）的相对贡献率为0.2% ~ 13.9%（0.4% ~ 3.8%），分配进入到各年限土壤POC（PON）中的比率为0.7% ~ 13.8%（1.4% ~ 9.9%）；经随后150 d冻结后，秸秆碳分配进入到0 a和12 a土壤POC和PON中的比率明显下降，秸秆氮分配进入到0 a和85 a土壤PON中的比率明显下降，而分配进入到其它年限土壤POC（PON）中的比率仍有增加。秸秆碳在土壤POC中的分配比率与土壤有机碳、全氮和碱解氮含量呈显著负相关，与土壤C/N、有效磷和微生物生物量碳含量呈显著正相关，秸秆氮在土壤PON中的分配比率与土壤有机碳含量呈显著负相关。研究表明东北典型黑土开垦种稻年限越长，土壤有机碳、全氮和碱解氮含量相对较低，而土壤C/N、有效磷和微生物生物量碳含量相对较高，秸秆碳氮在土壤颗粒有机质中的分配比率越大，土壤颗粒有机质对水稻秸秆添加的响应越为敏感。
【Objective】Particulate organic matter is an important component of soil labile organic matter and a sensitive index to evaluate a change of the soil organic matter. The climate in Northeast China is very cold, so, paddy fields therein have a short flooding period and a long non-flooding period since the soil is frozen for most of the time. However, little research has been carried out on the incorporation of exogenous rice straw carbon (C) and nitrogen (N) into particulate organic matter in black soil with different rice planting years. 【Methods】A 300-day incubation experiment was conducted, in which dual-isotope-labeled (13C/15N) rice straw was added to a cultivation chronosequence of paddy soils ranging from 0 to 85 years (0 a, 12 a, 35 a, 62 a and 85 a). Flooding incubation experiments were conducted at a temperature of 20 °C and a 1 cm water-flooded layer in a laboratory for 150 days while the freezing incubation experiments were also carried out for 150 days under a soil temperature of -15 °C and water-saturated. 【Result】 Throughout the entire incubation period, the contents of particulate organic carbon (POC) and particulate organic nitrogen (PON) in all paddy soils from the samples with and without rice straw were lower than that in the control soil (0 a). The contents of POC and PON in all soils from the samples with rice straw increased after 5 days of flooding incubation, but they did not show a consistently increasing trend in the subsequent incubation period. For paddy soils of different rice planting years, the relative contribution of the added rice straw C (N) to POC (PON) was 0.2%-13.9% (0.4-3.8%). 0.7%-13.8% (1.4%-9.9%). At the end of freezing incubation, incorporation of the rice straw C into POC in control soil (0 a) and 12-year paddy soil (12 a) decreased significantly compared with that at the end of flooding incubation. Also, the added rice straw N into PON in control soil (0 a) and 85-years paddy soil (85 a) decreased while the added rice straw C (N) into POC (PON) in other rice cultivating years was still increasing. The incorporation of the added rice straw C into POC was significantly negatively correlated with soil organic C, total N and alkaline N, and significantly positively correlated with soil C/N, available phosphorus and microbial biomass C. In addition, the incorporation of straw N into soil PON showed a significant negative correlation with soil organic C content. 【Conclusion】The study showed that the longer the years of rice planting in a typical black soil of northeast China, the contents of soil organic C, total N and alkaline N were relatively low, while the soil C/N, available phosphorus and microbial biomass C contents were relatively high. The greater the incorporation of straw C and N into soil particulate organic matter, the more the response of soil particulate organic matter to rice straw addition.
Wu Yihui, Wagn hongfei, Zhang Rui, An Jing, zhangyuling, Yu Na, Zou Hongtao. Incorporation of Carbon and Nitrogen from Rice Straw into Particulate Organic Matter in Black Soil with Rice Planting[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202203030009,[In Press]