Effect of nitrogen and phosphorous rates on fertilizer use efficiency in lettuce and spinach

Abstract

In this study, Lettuce (Lactuca Sativa) and Spinach (Spinacea Oleracea) were used as a case study vegetable crop to 
compare models for estimating Fertilizer Use Efficiency based on nitrogen and phosphorous fertilizer and nitrate 
concentration. Field studies were conducted to measure yield, nitrate, Fertilizer Use Efficiency, response to applied 
Nitrogen and phosphorous fertilizer in two plants. The area was located between 25° 21 E longitude and 51˚38 N 
latitude in the North of Varamin city, (Tehran province, Iran) in the alluvial plain of Varamin. Soils family were fine, 
mixed, active, thermic, typic haplocambids based on Soil Taxonomic system (1999). Plants were received five rates of 
Nitrogen (0.0, 150, 200, 250 and 300 kg Nha-1) as a urea in split applications and five rates of Phosphorous (0.0, 37.5, 50, 
62.5 and 75 kg P2O 5 ha-1) as a triple super phosphate (TSP). Data for plant fresh mass (tonha-1) and Nitrate uptake 
(nitrate) (mgkg-1) were recorded. Models were described the data for cultivar quite well, with correlation coefficients of 
0.80 and above. All of models for Lettuce and Spinach production were compared graphically and analytically. The 
model coefficients were then used to make improved estimates of fertilizer recommendations for field production of 
Lettuce and Spinach in Iran. Results showed that most suitable mode for prediction of fertilizer use efficiency was 
Y=16.77+0.0522N+0.0576P (R2=0.81) in lettuce (N: kg and P: kg P2O5ha-1 in lettuce. Based on we could predicted 
fertilizer use efficiency that help to agricultural practice management until nitrogen and phosphorous fertilizers used 
suitable and avoid leaching of nitrogen in lettuce culture.