FERTILIZERS WITH ORGANIC SUBSTANCES AND AGROCHEMICAL EFFECTS

ABSTRACT

Humic substances (humic and fulvic acids) are widespread, being present in soil, water, lake sediments, peat, and different coal. Therefore, there is a great interest for their immense role in terrestrial and aquatic systems, as well as their bio-stimulatory effects on plant growth. Humic substances, through their positive effects on plant nutrition and by increasing the tolerance to abiotic and biotic stress, lead to higher yields and superior quality crops. Their role in agriculture is essential, but humic substances are of interest in other areas such as environmental protection and medicine. This paper presents a novel fertilizer (called UANHUM) which contains humic substances (humic and fulvic acids). These organic substances were extracted from lignite and embedded in an NPK + Mg + B matrix. A set of agrochemical tests were conducted in order to assess the effects of the foliar fertilizer on tomatoes, maize, sunflower, soy, sugar beet, apple, and grape vine. In the case of foliar application of UANHUM fertilizer, experimental data showed yield increases ranging from 15.4% for apple to 30.6% for field tomatoes, as compared with the unfertilized control. Also, there were observed changes in the photosynthesis process - significant increases in assimilable pigments: 28.3% for tomatoes, 14.2% for corn, 20.6% for sugar beet, 15.8% for soybean, 14.4% for sunflower 12.8% for apple and 20.1% for grapevine, as compared with the unfertilized control. The results presented in this study demonstrate that fertilizing formulations which contain humic substances along with main nutrients (nitrogen, phosphorus and potassium), secondary nutrients (magnesium), and micronutrients (boron) are well assimilated by plants and have a significant contribution to yield increase and crop quality improvement.

Keywords: fertilizers, biostimulants, humic substances, foliar fertilizers