DataSheet_1_Straw and phosphorus applications promote maize (Zea mays L.) growth in saline soil through changing soil carbon and phosphorus fractions.docx

IntroductionStraw return has been widely recognized as an important carbon (C) enhancement measure in agroecosystems, but the C-phosphorus (P) interactions and their effects on plants in saline soils are still unclear.
MethodsIn this study, we investigated the effects of straw return and three P application levels, no P fertilizer (Non-P), a conventional application rate of P fertilizer (CP), and a high application rate of P fertilizer (HP), on maize growth and soil C and P fractions through a pot experiment.
Results and discussionThe results revealed that the dry matter weight of maize plant was no difference between the two straw return levels and was 15.36% higher under HP treatments than under Non-P treatments. Plant nutrient accumulations were enhanced by straw addition and increased with increasing P application rate. Straw application reduced the activities of peroxidase (POD), superoxide dismutase (SOD), catalase, and the content of malondialdehyde (MDA) in maize plants by 31.69%, 38.99%, 45.96% and 27.04%, respectively. P application decreased SOD, POD activities and MDA content in the absence of straw. The contents of easily oxidized organic carbon (EOC), particulate organic carbon (POC) and the ratio of POC/SOC in straw-added soils were 10.23%, 17.00% and 7.27% higher, respectively, than those in straw-absent soils. Compared with Non-P treatments, HP treatments led to an increase of 12.05%, 23.04% in EOC, POC contents respectively, while a decrease of 18.12% in the contribution of MAOC to the SOC pool. Straw return improved the P status of the saline soil by increasing soil available P (14.80%), organic P (35.91%) and Ca2-P contents (4.68%). The structural equation model showed that straw and P applications could promote maize growth (indicated by dry matter weight, P accumulation, antioxidant enzyme activity and MDA content) through improving soil C and P availabilities.
ConclusionThis study provides evidence that straw return together with adequate P supply in saline soil can promote crop nutrient accumulation, attenuate the oxidation damage on crop growth, and be beneficial for SOC turnover and soil P activation.

引言
秸秆还田已被广泛认为是农田生态系统中重要的碳（carbon, C）固持提升措施，但盐渍土壤中的碳-磷（phosphorus, P）相互作用及其对植物的影响仍不明晰。

材料与方法
本研究通过盆栽试验，探究了秸秆还田与3个磷（phosphorus, P）施用水平——不施磷肥（Non-P）、常规磷肥施用量（CP）、高磷肥施用量（HP）——对玉米生长及土壤碳、磷组分的影响。

结果与讨论
结果显示，两种秸秆还田水平下玉米植株干物重无显著差异，HP处理组的玉米干物重较Non-P处理组高15.36%。秸秆还田可提升植株养分积累量，且该积累量随磷施用量的增加而升高。秸秆还田使玉米植株的过氧化物酶（peroxidase, POD）、超氧化物歧化酶（superoxide dismutase, SOD）、过氧化氢酶活性以及丙二醛（malondialdehyde, MDA）含量分别降低31.69%、38.99%、45.96%与27.04%。在未施加秸秆的处理组中，增施磷肥可降低SOD、POD活性与MDA含量。与未施加秸秆的土壤相比，秸秆还田土壤的易氧化有机碳（easily oxidized organic carbon, EOC）、颗粒态有机碳（particulate organic carbon, POC）含量以及POC/SOC比值分别提升10.23%、17.00%与7.27%。与Non-P处理组相比，HP处理组的EOC、POC含量分别提升12.05%、23.04%，而矿物结合态有机碳（MAOC）对土壤有机碳（SOC）库的贡献率下降18.12%。秸秆还田通过提升土壤有效磷（available P，14.80%）、有机磷（organic P，35.91%）与Ca2-P含量（4.68%），改善了盐渍土壤的磷素状况。结构方程模型分析结果显示，秸秆还田与磷肥施用可通过提升土壤碳、磷有效性，促进玉米生长（以干物重、磷素积累、抗氧化酶活性及MDA含量为表征指标）。

结论
本研究证实，盐渍土壤中秸秆还田配施适量磷肥可促进作物养分积累，缓解氧化胁迫对作物生长的损害，同时有利于土壤有机碳周转与土壤磷素活化。