Optimisation of Silviculture Using Bioconversion of Sawdust Pulp in Krasnoyarsk Forest-Steppe
The effect from addition of sawdust pulp substrates together with micro-doses of various mineral fertilizers in soil was assessed from transformation of soil nitrogen under Scots pine and Siberian spruce saplings. Readily hydrolysable nitrogen exceeded hardly hydrolysable nitrogen under most of variations of fertilizers used when sawdust pulp substrates has been added. This point to high biological activity of soil and optimal environment for microbial enzymatic biodegradation of sawdust pulp substrates under the saplings. We found direct effect of ammonia nitrogen in soil of nursery on enzymatic nitrogen in needles of pine and spruce. Addition of sawdust pulp substrates significantly increased total and enzymatic nitrogen in the sapling needles. Concentration of total nitrogen in the needles of pine and spruce rose up to 21.7 and 27.6 mg per g of oven-dry substance, when grown on sawdust pulp substrates. On the contrary, the total nitrogen concentration in the needles of control species was less than 10.3 and 9.1 mg per g of oven-dry matter, respectively. Maximal concentrations of enzymatic nitrogen in pine needles (12.5-14.6 mg per g of oven-dry matter), composing 67.5-75% of the total nitrogen were found when carbamide, ammonia sulfate, German saltpeter and diammophoska had been added to sawdust pulp substrates. Maximal concentrations of enzymatic nitrogen in spruce needles (17.9-19.0 mg per g of oven-dry matter), composing 71.4-80.5% of the total nitrogen were found when German saltpeter, ammonia sulfate and carbamide had been added. Thus, sawdust pulp substrates with micro-doses of ammonia sulfate, carbamide, diammophoska and German saltpeter were most efective for nitrogen accumulation in the needles.