Lignohumate® protects crops from pests without negative effects of pesticides
The long-term application of various chemical products, especially pesticides, can have a large number of detrimental effects to the environment such as decrease in biological diversity, accumulation of chemicals in animal tissues, cancerogenic effects in humans, soil and water pollution. Despite low price and immediate effect, long-term effects of pesticides can lead to substantial losses in agriculture, economy, and environment.
Today ‘soft’ means of indirect impact are becoming more and more popular to maintain high quality yeild. Their mechanism is as follows: soil or plants are treated with certain additives which do not kill the pests directly, but rather promote the activity of their natural enemies – bacteria. One of such examples is a commonly used humic product Lignohumate®.
Bacterial activity is closely related to gas exchange (CO2, CH4, N2, NO3X, etc.) between soil and the atmosphere. Hence, monitoring the exchage rate of these gases can be used to assess soil quality when applying pesticides, Lignohumate and other products. Undoutedly, such studies should be supplemented with microbiological experiments to control the quantity and composition of bacterial community. In the frame of this work we have conducted a comparative analysis of the effect of pesticides and Lignohumate on microbial communities in rice field soils of Bali Island.
The results showed that application of Lignohumate® in various concentrations resulted in the increase in CO2 by 30% (soil respiration), absorption of N2 from the atmosphere (nitrogen fixation) and release of CH4 (methanogenesis). It should be noted that low concentrations of Lignohumate® promoted an increase in NO3X (denitrification), whereas high concenrations of Lignohumate® contributed to its reduction. Nitrogen is one of the most important elements of mineral plant nutrition, which means, agriculturally, nitrogen accumulation in soil (nitrogen fixation) is beneficial and nitrogen loss (denitrification) is detrimental. Thus, application of Lignohumate® in concentrations higher than 0.025 mg/g has a positive impact on soil nitrogen balance.
Intensity of soil microbial processes under various application rates of Lignohumate® as percentage of control
Unlike pesticide application only where denitrification value was constant, combined application of Lignohumate® and pesticides increased nitrogen fixation intensity. Thus, this product can be recommended to reduce toxic effects of pesticides on microbial community. It should be highlighted that increase in all microbiological indexes with both products applied indicates favourable conditions for microbial pesticide decomposition with application of Lignohumate®.
In conclusion it can be noted that Lignohumate® acts as the source of organic matter, which promotes microbial activity. Besides, Lignohumate® stimulates microorganisms in soils contaminated with pesticides, thereby contributing to pesticide decomposition as well as having favourable impact on soil nitrogen balance by increasing its accumulation and recuding its loss.
In this context Lignohumate® can be considered as a means of improving soil nitrogen balance and activating microbial part of agrobiocenosis after stress. However, determination of its effective application rates requires consideration of concrete soil sonditions, preliminary laboratory tests and further research of its effect on microorganisms. One should also take into consideration that this product can enchance emmission of greenhouse gases, namely, carbon dioxide and methane.
L.A. Pozdnyakov, A.L. Stepanov, M.E. Gasanov, M.V. Semenov, O.S. Yakimenko, I.K. Suada, I.N. Rai, N.M. Shchegolkova. Effect of Lignohumate on Soil Biological Activity on Bali island, Indonesia // Eurasian Soil Science, 2020 (in press)