Macro and Microelements in Leaves of ‘Meredith’ Peach Cultivar Supplied with Biochar, Organic and Beneficial Biofertilizer Combinations

The use of biochar in the cultivation of fruit trees has a short history, and therefore there is a little information on this subject in the literature. The use of a small dose of biochar (2000 kg/ha) in our research has shown that it is an effective and economically justified dose. This is especially with the combination of a low dose of biochar with organic fertilization, which gives very good results in the fertilization of peach trees. It is best seen in the example of nitrogen.

−1 had the greatest impact on the potassium (K) content in sesame leaves at the first harvest. It also modified the nitrogen content in the leaves to a lesser extent. However, the chemical analysis of the second harvest of sesame did not show a significant increase in nitrogen, potassium, phosphorus, calcium or magnesium. In our study, the concentrations of nitrogen, phosphorus and potassium in peach leaves varied markedly, both under the influence of the applied biochar and organic fertilization. In the case of iron (Fe), the leaves of peach trees fertilized with biochar had a lower concentration of this element (66.5) than the leaves of control trees (74.1). Gale and Thomas [

Abutilon theophrasti

), stated that after using biochar in doses greater than 10 t ha-1, the nitrogen (N) content in the leaves decreased significantly (by approx. 30%). On the other hand, the boron content in the leaves after applying biochar at 10 t ha−1 increased twofold. In our study, the boron content increased in the subsequent years of the experiment, to the greatest extent after the combined application of biochar and the organic fertilizer (from 21.3 to 31.7); these differences were statistically significant. Research by Adekiya et al. [−1), noted that with an increase in the dose of biochar to the soil, the fresh and dry weight of wheat plants increased and the concentration of K in the tested plants also increased (1.24–1.49), when compared to the control plants (1.14), and the differences were statistically significant. In an experiment conducted in the Experimental Orchard in Dąbrowice, we found the highest level of K in the leaves of those peach trees where biochar was applied in combination with organic fertilization (2.47). The combined use of biochar and organic fertilization significantly increased the yield of pear fruit and the estimated leaf chlorophyll content (SPAD) relative to the control (Schaffert and Percival [

Milošević et al. [ 18 ], comparing the effects of organic and inorganic fertilization, showed that the applied manure had a greater effect on the nitrogen content in apricot leaves than mineral NPK fertilization. In contrast, the concentrations of P and K in the leaves of the plants treated with the mineral fertilizer were higher than in the case of fertilization with manure. In our study, we observed, over the three consecutive years, an increasing nitrogen content in peach leaves as a result of applying biochar in combination with organic fertilization, but the differences were not statistically significant. However, the doses of biochar and organic fertilizer were lower than in the experiment by Adekiya et al. [ 12 ]. The use of biochar as reported by Gunes et al. [ 19 ] increased the concentrations of nitrogen, phosphorus and potassium in lettuce leaves, and at the same time decreased the content of iron, copper, zinc and manganese. In the third year of our own research, the highest content of copper, zinc, manganese, calcium and boron was observed in tree leaves in combinations where biochar was used. Gunes et al. [ 20 ], using pyrolysed (at four temperatures) biochar, found that the concentrations of phosphorus and potassium in lettuce were the highest after applying to the soil biochar obtained at temperatures of 300 and 350 °C. The concentrations of these elements were higher in the control plants. Studies of some authors have indicated that the application of biochar to calcareous and sandy soils significantly increased the concentrations of nitrogen and phosphorus in zucchini fruit and plants, and improved soil fertility [ 14 ]. The results obtained by Saletnik et al. [ 15 ] showed a positive effect of biochar on the potassium content in plants, and its concentration increased with the increase in the dose of biochar (10, 15, 20 g) applied to the soil. Moreover, the combined use of biochar with ash significantly increased the potassium content in the leaves of the tested plants. Significant differences in the concentrations of phosphorus and calcium in plants, compared to the control plants, were also evident after the combined application of biochar and ash. Wacal et al. [ 21 ] noticed that biochar in a dose of 50 t hahad the greatest impact on the potassium (K) content in sesame leaves at the first harvest. It also modified the nitrogen content in the leaves to a lesser extent. However, the chemical analysis of the second harvest of sesame did not show a significant increase in nitrogen, potassium, phosphorus, calcium or magnesium. In our study, the concentrations of nitrogen, phosphorus and potassium in peach leaves varied markedly, both under the influence of the applied biochar and organic fertilization. In the case of iron (Fe), the leaves of peach trees fertilized with biochar had a lower concentration of this element (66.5) than the leaves of control trees (74.1). Gale and Thomas [ 22 ], using different doses of biochar in the cultivation of velvetleaf (), stated that after using biochar in doses greater than 10 t ha, the nitrogen (N) content in the leaves decreased significantly (by approx. 30%). On the other hand, the boron content in the leaves after applying biochar at 10 t haincreased twofold. In our study, the boron content increased in the subsequent years of the experiment, to the greatest extent after the combined application of biochar and the organic fertilizer (from 21.3 to 31.7); these differences were statistically significant. Research by Adekiya et al. [ 12 ] confirms the influence of the combined application of biochar with organic fertilization on increasing the phosphorus content in radish leaves. As reported by Amin and Eissa [ 14 ], the use of biochar (6.3 g per pot) increased the concentration of nitrogen (N) in zucchini fruit by 39% relative to the control but increasing the dose of biochar to 12.6 and 26.5 g did not cause greater accumulation of nitrogen in the fruit. Irrespective of the dose, biochar did not affect nitrogen accumulation in the plants. Neither did biochar increase the phosphorus (P) content in zucchini fruit, but when applied at a dose of 12.6 g per pot it increased the phosphorus content in plants by 55% relative to the control. In our research, the use of biochar did not increase the phosphorus content in peach leaves. However, organic fertilizer increased the content of this element. A higher P concentration was recorded in all combinations where organic fertilization was applied. Amin [ 23 ], analyzing the effects of three doses of biochar (20, 40 and 60 t ha), noted that with an increase in the dose of biochar to the soil, the fresh and dry weight of wheat plants increased and the concentration of K in the tested plants also increased (1.24–1.49), when compared to the control plants (1.14), and the differences were statistically significant. In an experiment conducted in the Experimental Orchard in Dąbrowice, we found the highest level of K in the leaves of those peach trees where biochar was applied in combination with organic fertilization (2.47). The combined use of biochar and organic fertilization significantly increased the yield of pear fruit and the estimated leaf chlorophyll content (SPAD) relative to the control (Schaffert and Percival [ 24 ]). Increased chlorophyll content in leaves (SPAD), resulting from the use of biochar in wheat cultivation, was also observed by Salim [ 25 ]; the application of 2% biochar to the soil increased the degree of leaf colouring by 24%. The addition of 5% biochar to a sandy soil increased the colour of the leaves by 17%, compared to the control plants. Earlier, our own research conducted on peach trees showed [ 26 ] the beneficial effect of the combined use of biochar and organic fertilization on the leaf size as well as the diameter of the trunk. In addition, in the third year after application, a significant increase in yield and fruit quantity was observed. The proposed treatments may be useful in fruit production using organic methods.