Abstract
There are currently many problems related to excessive fertilizer application, low fertilizer-use efficiency and lack of an agricultural labor force for cotton production in China. Therefore, the objective of this paper was to explain the optimal application time for once fertilization based on cotton nutrient accumulation of nitrogen, phosphorus and potassium to provide technical support for simplified fertilization management in cotton production. A 2 yr field experiment and a 1 yr pot experiment were conducted with fertilizer (225, 67.5, and 225 kg ha−1 of N, P2O5, and K2O, respectively) applied once at 0 (FT1), 5 (FT2), 10 (FT3), 15 (FT4), or 20 (FT5) d after the appearance of the first flower and a triple application (preplant 30%, first bloom 40%, and peak bloom 30%) as the conventional control (FT6). The results showed that FT1 exhibited the greatest nutrient accumulation speed for both the average (5.81, 1.22, and 5.74 kg ha−1 of N, P2O5, and K2O, respectively) and the maximum (6.31, 1.44, and 6.24 kg ha−1 of N, P2O5, and K2O, respectively) during the fast accumulation period. Moreover, among the different treatments, FT1 exhibited the greatest nutrient recovery and partial productivity. The results suggest that applying the minimum amount of fertilizer at the appearance of the first flower is optimal for maximizing nutrient utilization while minimizing environmental disturbance.
Highlights
There are currently many problems related to excessive fertilizer application, low fertilizer-use efficiency and lack of an agricultural labor force for cotton production in China
There was no significant effect of once fertilizer application on the N status of plants at squaring (37 DAE), but plant N status was significantly affected during all reproductive phases
The results of the present study showed that the accumulation of cotton plant nitrogen (CPN), Cotton plant phosphorus (CPP) and CPK was delayed, the fast accumulation period (FAP) was shorter, the speed in terms of both VT and VM was greater, and the subsequent plant nutrient accumulation was greater as the once fertilizer application timing was delayed compared with no delay, indicating www.nature.com/scientificreports
Summary
There are currently many problems related to excessive fertilizer application, low fertilizer-use efficiency and lack of an agricultural labor force for cotton production in China. Compared with conventional fertilizer application practices, minimum applications of slow/ controlled-release fertilizers have been shown to increase the yield and nitrogen-use efficiency (NUE) of maize as well as both wheat and rice significantly by 3.1–31.7% and 6.2–86.6%, respectively[8]. Once fertilizer applications at first bloom (the stage at which 50% of plants presented flowers) reduced labor costs without reducing yields[6]. We hypothesized that once fertilizer application applied relatively early (i.e., on the day the first flower opened in the field or at the peak squaring stage) is beneficial for improving the accumulation, distribution and use of the main nutrients (and it is easy for farmers to control fertilizer application timing) and for reducing excessive nutrient losses because of the small plant canopy under the new cropping management system. The objective of this study was to verify whether the appearance of the first bloom is the optimal timing for once fertilizer applications in terms of the accumulation, distribution and use of the major nutrients concerning sustainable production
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