Effect of biochar and microbial inoculant on the element compostion and element yield of maize on acidic and on calcareous sandy soils

Abstract

Effect of biochar, inoculated biochar, biochar+inoculant fixed on conventional carrier, and inoculant application was studied on element concentration and uptake of maize at two experimental stations of the Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences on calcareous sandy soil in Orbottyán and on acidic sandy soil in Nyírlugos. The four different treatments were set up at four different levels: 0, 3, 15 and 30 t ha-1 biochar, and 0-4x1011-1x1013 CFU ha-1 inoculant depending on treatment combinations. The 4 replications resulted in 64 plots carried out in random block design at both sites. At the edges of the plots measuring 20 m2 (4 x 5 m), 1 m wide margin was left, thus the net area of the plots were 6 m2 (2 x 3 m). The fertilization was done using half of the recommended NPK mineral fertilizer doses. Precipitation in the vegetation period was far below the 50-year average and the optimal water demand of maize, thus crop yields remained low, especially on the acidic sandy soil. Preparation for the tests, as well as the element composition of plant samples were determined according to Hungarian Standards. Treatments did not alter N and Mg concentrations in aboveground plant tissue. Due to increasing rates of treatments involving biochar, phosphorus content increased slightly on acidic soil in the aboveground parts of maize, whereas on calcareous soil it basically decreased in stem+leaves, but the difference was significant only in the biochar+inoculant treatment. K content in the stem+leaves spectacularly increased by 61% on acidic soil and by 87% on calcareous soil at the highest doses of biochar. Ca content of plants on calcareous soil was higher, which decreased slightly, whereas on acidic soil it increased due to biochar treatments. Zn content in the stem+leaves decreased at both sites due to rising biochar rates. Increasing doses of inoculant solely did not cause any changes in plant composition. Generally increasing yields due to biochar treatments resulted in more remarkable differences in the amount of uptaken elements by maize. The increment was more than 2 times higher in the case of N and K uptake at the highest biochar treatment level on acidic soil, whereas for P, Ca and Mg it was 67%, 73% and 57%, resp. in the leaves+stem and 2-3 fold in the grain, compared to control. The latter was also true for the uptake of Zn, whereas in the stem+leaves there was only a slight increase. On the calcareous soil N uptake by the stem+leaves increased by about 40%, whereas P, K and Ca uptake by grain slightly decreased. In the case of Mg and Zn, the treatments involving biochar had practically no effect. Combined application of vaccine together with biochar in some cases resulted in the highest N, P and K uptake by maize, thus the mutual positive effects of the two substances can be assumed. The solely applied inoculant could also promote the uptake of N.