Applying control-released fertilizer of whole growth duration in seedling-raising pot to effectively decrease the risk of N loss in the paddy field

Objectives Nitrogen application in paddy fields ineluctably causes N loss to the environment. Here, we studied fertilizer application in seedling-raising pots without changing the application rate, aiming to find an effective way for achieving high yield and decreasing N contents in surface water of paddy fields.

Methods In Anlu City, Hubei Province, field experiments were conducted using rice cultivar Huaxia Xiangsi as test materials. The three fertilization treatments were conventional seedling-raising and no fertilization in the field (CK), conventional seedling-raising and fertilization in the field (FF), and applying all fertilizers in seedling-raising pots (PF). Twenty-eight (28) days after seedling, rice seedling growth and nutrient contents and the nitrogen contents in field surface water during basic fertilization, tillering, and panicle fertilization stages were measured. Rice yields and yield components were investigated at harvest.

Results Compared with FF, PF increased underground biomass and P contents, aboveground N, P, and K contents of rice seedlings by 77%, 41.65%, 14.69%, 17.47%, and 3.28%, respectively, and 1000-seed weight and yield by 6.82% and 10.78%. Using PF, the total N, NH₄⁺-N, and NO₃^–-N concentration in field surface water was similar to CK but (P<0.05) lower than FF during the whole growing period of rice. PF performed better in reducing nitrogen loss in the rice field than the conventional fertilization strategy.

Conclusions Applying control-released fertilizer in seedling-raising pots at a standard rate rather than on the field proved effective in culturing good quality seedlings with high nutrient storage and increasing rice yield. The non-application of fertilizer on the field kept N concentration in the field surface water low, reducing N loss to the environment during the whole rice growing period.