The application of nano−clinoptilolite based nitrogen fertilizer mixed with urea promotes nitrogen balance and enhances economic and ecological benefits in paddy fields

Abstract

Reducing the size of clinoptilolite accentuates its structural attributes, notably mesoporosity and the silica−aluminum ratio, which enhanced its capabilities as an efficient adsorbent and modifier. This research aims to utilize the augmented small−size effect of clinoptilolite to develop a high−performance nano−clinoptilolite based nitrogen (N) fertilizer, to substitute an equivalent amount of urea. To this end, a two−year field experiment was conducted using a single−factor randomized complete block design, involving five different nano−clinoptilolite based N fertilizer mixed with urea (ZN) ratios: control treatment (100% Urea, CK); 20% Z & 80% Urea (Z2N8); 30% Z & 70% Urea (Z3N7); 40% Z & 60% Urea (Z4N6); 50% Z & 50% Urea (Z5N5). This study explored the effects of ZN on ammonia volatilization (AV), N runoff loss, N accumulation, N balance, yield, and ecological benefits in paddy fields. The results showed that Z2N8, Z3N7, Z4N6, and Z5N5 reduced the total AV losses by 8.57%, 20.52%, 30.20%, and 37.13% (two−year average), and reduced runoff losses by 23.29%, 29.93%, 39.66%, and 43.76%, respectively. Additionally, Z2N8, Z3N7, Z4N6, and Z5N5 increased whole−plant N accumulation by 24.32%, 16.84%, 9.00%, 4.85%, and raised rice yield by 15.28%, 10.28%, 6.99%, 5.05%, respectively. This result indicates that ZN can enhance N utilization, although the effectiveness diminishes with an increased application ratio. Furthermore, Z2N8, Z3N7, and Z4N6 lowered N surpluses by 48.77%, 25.84%, and 3.17%, respectively, while Z5N5 resulted in an increase in N surplus by 9.61% relative to the control. Compared to CK, nano−clinoptilolite based N fertilizer replacing 20% of urea (Z2N8) increased income by 14.75%, reduced environmental damage cost by 8.77%, and ultimately boosted net economic benefits by 5.33% and net economic and ecological benefits by 5.75%. In conclusion, Z2N8 can be contemplated as a compound fertilizer to be applied to farmland to enhance both economic and ecological benefits.