В условиях влажно-субтропической зоны России (сочинское Черноморское побережье) в многофакторном полевом опыте проведено изучение кислотно-основной буферности бурых лесных кислых почв многолетних модельных агроценозов чая. Сравнили показатели почв разной степени подкисления в результате 25-летнего (1986-2011 г.) применения NРК -удобрений и после 8-9 лет их отмены (с 2012 г.). Почва, получившая средний уровень подкисления (снижение рН на 0,5-0,7 ед.) при удобрении одинарными дозами ( N Р К ), имела наименее выраженные отличия от контроля ( NРК ) и фона (лес). В отсутствии удобрений она еще более приблизилась к ним по всем показателям, при ослаблении кислотности на 0,2 ед. рН . Это свидетельствует о допустимом уровне такой нагрузки. Сильно подкисленные почвы (снижение рН на 1,1-1,3 и 1,3-1,5 ед.) в результате длительного внесения двойных и тройных доз NPK -удобрений значительно отличались от контроля и фона. В кислотном интервале площадь буферности и степень приведенной буферной способности снизились в 2-2,5 раза, а средняя буферная емкость, напротив, выросла в 1,3-1,4 раза за счет активизации высокоемкой железистой при истощении алюминиевой буферной зоны. После снятия нагрузки удобрениями произошли: ослабление кислотности на 0,4-0,5 ед. рН ; увеличение площади кислотной буферности на 25-30 %, рост в 1,3 раза степени кислотной приведенной буферной способности и индекса кислотно-основного равновесия, повышение средней буферной емкости к щелочным нагрузкам при снижении к кислотным нагрузкам (на 10-20 %); повышение емкости алюминиевой буферной зоны при сохранение резервов железистой зоны буферности. Постепенное возвращение к исходным характеристикам, свойственным нативным почвам (фону), свидетельствовало о способности самовосстановления даже сильно подкисленных почв после снятия агрогенного прессинга. In the conditions of the humid subtropical zone of Russia (Sochi Black Sea coast), in a multifactorial field experiment, the acid-base buffering of brown forest acid soils of perennial model tea agrocenoses was studied. Compared the indicators of soils acidified to varying degrees as a result of the 25-year (1986-2011) application of NRK fertilizers and after 8-9 years of their abolition (since 2012). The soil that received an average level of acidification (pH reduction by 0.5-0.7 units) when fertilized with single doses (N120-200 P60 K50) had the least pronounced differences from the control (N0P0K0) and the background (forest). In the absence of fertilizers, it came even closer to them in all indicators, with a decrease in acidity by 0.2 pH units. This indicates the acceptable level of such a load. Highly acidified soils (a decrease in pH by 1.1-1.3 and 1.3-1.5 units) as a result of prolonged application of double and triple doses of NPK-fertilizers significantly differed from the control and background. The buffering area and the degree of reduced buffering capacity in the acid range decreased by 2-2.5 times; the average acid buffer capacity increased by 1.3-1.4 times due to the activation of the high-capacity ferruginous and depletion of the aluminum buffer zone. After removing the load with fertilizers, the following occurred: a decrease in acidity by 0.4-0.5 units. pH; an increase in the area of acid buffering by 25-30%; increase in 1.3 times the degree of acid buffering capacity and acid-base balance index; an increase in the average buffer capacity to alkaline loads while decreasing to acid ones (by 10-20 %); increasing the capacity of the aluminum buffer zone and maintaining the reserves of the ferruginous buffer zone. The gradual return to the initial characteristics characteristic of native soils of this zonal subtype (background) testified to the ability of self-healing even of highly acidified soils after the removal of agrogenic pressure.

The effects of application of calcium-containing natural fertilizer on the functional state of the tea plant were studied. Application of calcium resulted weakening of the negative effects of high temperatures and water deficiency due to an increase in its heat resistance (on average by 30 - 40%), an increase in catalase activity (on average 5 - 10 %), as well as adaptive rearrangement of pigment ratio to increasing the content of carotenoids, chlorophylls and the their functional activity. In general, the more efficient functioning of the signaling intracellular network due to the calcium application provided better adaptability of plants to extreme conditions and more efficient recovery after subsequent rehydration, which in a whole contributed to an increase in shoot growth activity (on average 20%) and an increase in yield by an average of 27 - 33%.

Based on long experience with fertilizers on tea culture in the conditions of the Sochi Black Sea coast, the buffer properties of brown forest acid soils, acidified in various degrees as a result of the use of single (111), double (222) and triple (333) doses of NPK were studied. The total load of nitrogen fertilizers (the main factor of acidification) for 26 years of use was 3.8-7.6-11.4 tons N/ha. Comparison was made with the soil without fertilizers (000) and forest soil. The identical capacity of soil buffering relative to the hydroxyl load was revealed: shift by 1 and 2 pH units with the introduction of 2.5 and 10.0 mEq NaOH per 100 g of soil. Soil resistance to acid loads was increasing in the series: forest — 000 — 111 — 222 — 333. The highest buffer capacity under increasing proton load was found in soils with a high degree of acidification as a result of the use of double and triple doses of NPK. For them, a shift of 2 pH units was achieved by adding into the suspension about 12.5 mEq HCl per 100 g of soil, while for others it was about 7.5 mEq HCl per 100 g of soil. The resistance of some soils (222 and 333) to acid loads was higher than to alkaline loads, while the resistance of others (forest, 000, 111) on the contrary.

The dynamics of phosphorus supply of brown forest acidic soils in the humid subtropics of Russia under conditions of a long-term field experiments with 16 NPK-fertilizers combinations on tea culture was studied for 27 years. The trend of the changes (degree and speed) is represented graphically, by regression and correlation dependencies, approximating functions. A dose of phosphorus fertilizers of 60 kg/ha, with long-term systematic application in combination with the suffi cient doses of NK-fertilizers, provided a content of mobile phosphate in soil at an average level of 40- 60 mg/100 g (optimal) and a non-deficit phosphorus balance in the agrosystem. The application of 120-180 kg/ha of phosphorus fertilizers led to a 2-3 fold increase in the content of mobile phosphates (in the 0-20 cm soil layer), with an average rate of 30-40 mg/100 g for 10 years or 25-30 mg/100 g per ton of applied P fertilizers. “Overphosphating” of soils was expressed by proportional growth of total phosphorus. In the absence of phosphorus fertilizers, the high yield of tea was provided by the created pre-plant phosphorus reserve (with some depletion), effective in aftereffect.

ДИНАМИКА АЗОТНОГО ФОНДА БУРЫХ ЛЕСНЫХ КИСЛЫХ ПОЧВ ВЛАЖНЫХ СУБТРОПИКОВ РОССИИ В МНОГОФАКТОРНОМ ПОЛЕВОМ ОПЫТЕ С УДОБРЕНИЯМИ НА КУЛЬТУРЕ

Dynamics of changes in soil acid-base characteristics (pHKCl, hydrolytic acidity, exchangeable aluminum, exchangeable calcium and magnesium, the degree of base saturation) of brown forest acidic soils in tea plantations were studied based on a long-term (27 years) multifactorial fi eld experiment of 16 NPK-fertilizers combinations. The relationship of the process of soil acidifi cation with values of applied nitrogen fertilizers, as a leading factor, is represented in the form of regression and correlation dependencies, graphical and approximating mathematical models. The fi nal changes in the parameters and their speed against the backdrop of 1-2-3th doses of nitrogen fertilizers (singledose step 70-90-120-200 kg N ha-1 yr-1) with a total amount 3800-7600-11400 kg N ha-1 of applied N-fertilizers have been shown. Thus, depending on the N doses the soil pHKCl in the 0-20-cm layer decreased on the average from 0,5 to 0,8-0,9, with an average rate of 0,1 per 3-6 years, or 0,07-0,1 for each applied 1000 kg N ha-1. These changes are 1,5-2 times weaker in the 20-40-cm layer.