Optimum Rate and Deep Placement of Nitrogen Fertilizer Improves Nitrogen Use Efficiency and Tomato Yield in Nepal

Abstract

In Nepal, blanket fertilizer recommendations without considering diverse soil types, nutrient status, climate and crop management practices along with imbalanced fertilization practices by farmers, mainly “urea fertilizer,” have resulted in reduced nitrogen use efficiency (NUE) and productivity in tomato production. Optimizing the rate of nitrogen (N) fertilizer, application time and improved application methods could increase crop yields and NUE and reduce environmental costs. This study was conducted to identify the optimum N rate and application method for increased tomato yield and NUE. Multilocation trials (n = 28) conducted in a randomized complete block design with nine treatments across five districts included the omission of N, P and K (N0, P0, K0), variable N rates of 100, 150, 200 and 250 kg ha−1 (N-100, N-150, N-200 and N-250), use of urea briquettes (UB) with deep placement (UBN-150) and a control (CK). N input in UB was reduced by 25% from the recommended N rate of 200 kg ha−1 considering its expected higher NUE. Yield responses from an NPK omission plot revealed N as the most limiting plant nutrient. Applications of fertilizer at N-100, N-150, N-200 and N-250 increased tomato yield by 27%, 35%, 43% and 27%, respectively, over N0. Tomato yields responded quadratically to the added N fertilizers with optimum rates ranging from 150 to 200 kg ha−1 across districts. UBN-150 significantly increased tomato yield by 12% over N-150 and produced a similar yield to N-200 (the recommended rate). The highest partial factor productivity of nitrogen (PFPN) was observed at N-100 and the highest agronomic efficiency of N (AEN) was at N-200. Deep placement of UB at-150 increased PFPN by 8% and 21% and AEN by 27% and 21% compared with N-150 and N-200, respectively. These results have positive implications for developing efficient N fertilization strategies to increase tomato yields and reduce environmental impacts in Nepal.

Yield, Quality, and Nitrogen Leaching of Open-Field Tomato in Response to Different Nitrogen Application Measures in Northwestern China

“…When nitrogen was provided at a rate of 375 kg ha −1 , however, yields dramatically decreased (Table 1). Excessive nitrogen application significantly reduced the yield, which was consistent with studies reporting that when nitrogen application reaches a certain level, tomato yield decreases with continued increasing nitrogen application [27,28], which may be caused by increased osmotic pressure in the rhizosphere. The addition of controlled-release nitrogen fertilizer OPT maintained a continuous supply of inorganic nitrogen to the soil and significantly increased the yield of tomato.…”

A new approach to measure spatial variability of soil parameters and field technique to test-value specific fertilizer recommendations

“…Nitrogen is the most important nutrient element but also the most frequent deficit nutrient. Its inadequacy is considered to be a major cause of low crop yields in Nepal [15,16]. The average level of nitrogen was found to be low, some 56% of the households in the study area reported low levels of nitrogen in their soils.…”

Variations in Nitrogen Accumulation and Use Efficiency in Maize Differentiate with Nitrogen and Phosphorus Rates and Contrasting Fertilizer Placement Methodologies

“…The NAE (N agronomy efficiency), NUE (N use efficiency), and PFP N (partial factor productivity for the applied N) are commonly characterized for fertilizer use efficiency [15,27,53]. Fertilizer management strategies by optimizing the right rate, right source, right time, and right application method have obtained higher yield, N efficiency, and environmental quality [54]. In the current study, Deep band significantly increased NAE, NUE, and PFP N more than Broadcast and Side band (Table 1).…”