Effects of biochar and fertilizer application on soil properties and nutrient status of lettuce

Different ways of benefiting from plant wastes in agricultural production are developed. One of the methods is to convert wastes into biochar and use it as a soil regulator. This study was conducted to determine the effects of biochar produced from tomato ( Solanum lycopersicum L.) plant waste on soil fertility and nutritional status of the lettuce ( Lactuca sativa L.) plant. For this purpose, the combined effect of five different doses of biochar (0, 10, 20, 30, and 40 t ha -1 ) and three chemical fertilizers (control, half-dose NPK and full-dose NPK) were investigated. The research was conducted in two cultivation periods. Biochar was applied to the soil just in the first period. In the first period, applications increased electrical conductivity, organic matter content, total N, and concentration of available P, Zn, and Mn, and the exchangeable K and Mg in the soil. Biochar and chemical fertilizer applications positively affected the lettuce plant’s N, P, and K concentrations. In the second period, concentrations of the available P, Fe, Zn, Mn, Cu and exchangeable Ca, Mg in soil, as well as the N, P, Ca, Mg, Zn, and Cu concentrations of the plant are higher compared to the first period. It was determined that biochar application alone was not sufficient for the nutrition of the lettuce plant, chemical fertilizers should be used additionally. In lettuce cultivation, half-dose NPK was recommended in addition to 30 t ha -1 biochar. As a result, it was determined that biochar produced from tomato plant waste was an effective soil improver material and might be an alternative source of K. kg ha -1 K 2 O). Application amounts were determined according to local recommendations. Ammonium nitrate, mono ammonium phosphate, and potassium nitrate were used as sources of fertilizer. The study was established as factorial and four replicates according to the design of the randomized plot. The first cultivation period was terminated on 20 December 2016, with the cutting of lettuce plants from the root collars. Since biochar is a material whose effects are long-lasting, its residual effects were intended to detect. Therefore, after the plants were cut from the root collars, four lettuce seedlings were planted in the same pots on 11 January 2017. As in the first trial, chemical fertilizers were applied in the same doses. The second cultivation period was completed with the cutting of lettuce plants from the root collars on 1 March 2017. At the end of the trial, wet and dry weights (dried at 65 °C for 3 d) of the plants cut from the root collars were determined.