Impacts of Agricultural Land Reclamation on Soil Nutrient Contents, Pools, Stoichiometry, and Their Relationship to Oat Growth on the East China Coast

Abstract

Agricultural land reclamation of coastal tidal land (CTL) with organic amendments may modulate the soil properties, and therefore promote crop growth. However, the linkages between soil nutrient contents, pools, stoichiometry, and crop growth under the supplement of organic amendments in CTL is limited. In this study, six treatments including the control (CK), organic manure (OM), polyacrylamide plus organic manure (PAM + OM), straw mulching plus organic manure (SM + OM), buried straw plus organic manure (BS + OM), and bio-organic manure plus organic manure (BM + OM) were conducted to explore these linkages in newly reclaimed CTL in Jiangsu Province, eastern China. The results showed that the application of different soil reclamation treatments increased soil nutrient contents, pools, and modulated their stoichiometric ratio, which thus promoted the growth of oat. Soil under all reclamation treatments increased the contents of surface soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP), and the BM + OM treatment had the highest increase, which increased by 11.7–182.4%, 24.3–85.7%, 3.2–29.4%, respectively. The highest soil C pools were observed in the oat heading stage (36.67–41.34 Mg C ha−1), whereas the soil N and P pools were more stable during the oat growth period. Similarly, the highest surface soil C/N and C/P were observed in the oat heading stage (11.23–14.67 and 8.97–14.21), whereas the N/P in surface soil increased compared with the CK treatment during the oat growth period, with the exception of the filling stage. Land reclamation treatments significantly promoted oat growth by changing soil C, N, and P contents, pools, and stoichiometry, among which soil SOC, TN, TP, C/P, and N/P are more closely related to oat growth (p < 0.05).