Effect of fertilizers enriched with bio-based carriers on selected growth parameters, grain yield and grain quality of maize (Zea mays L.)

Low efficiency of nutrient use, especially nitrogen, from mineral fertilizers under the drought conditions is a worldwide problem in agriculture. Therefore, low-cost, and environmentally friendly technologies that improve the utilization of nutrients from applied fertilizers while increasing water availability to plants are urgently needed. The aim of our research was to prepare bio-based carriers composed from different ratios of natural hydroabsorbent (NHA), synthetic superabsorbent polymer (SAP), and zeolite. The commercial fertilizers (NP and NPK) were enriched with these carriers with subsequent determination of their ability to release nutrients and affect the growth of maize plants grown under drought conditions. The first (i) part of our experiment focused on the lab preparation of bio-based carriers followed by a testing of their abilities to release nitrogen into water in the lab conditions. The effect of selected carriers in the mixture with commercial fertilizers to the growth of maize were subsequently tested under the optimal and limited watering regime in the greenhouse pot experiment (ii). The control treatment (no fertilizer) and fertilization treatments were established, namely, single bio-based carrier (C2) and compound fertilizers (NP, NPK) and their mixture (C2-NP, C2-NPK). The effect of these fertilizers applied in two doses (at the level of 30 and 60 kg/ha N) on the yield and grain quality of maize (iii) was finally evaluated in a two-year field experiment (2020 – 2021). Based on the existing kinetic models, it was possible to the link nitrogen release to the structural variables of the composite carriers. A small volume of zeolite microparticles incorporated into the biopolymer network of the NHA and SAP carrier accelerated the nitrogen release in the lab experiment (i) and increased the maximum amount of released nitrogen in proportion to the zeolite content without significantly affecting the water-holding capacity. The results of the greenhouse pot experiment (ii) demonstrated that application of a bio-based carrier composed of 7 wt% SAP, 7 wt% zeolite and 86 wt% NHA in combination with NP and NPK fertilizers significantly increased chlorophyll content, the ability of maize plants to absorb radiation in photosystem II, and the weight of above-ground maize biomass under limited and optimal irrigation conditions. The C2-NPK increased grain weight, grain yield and protein content in the grain of maize under the field conditions (iii). Fertilizers enriched with bio-based carrier are a promising alternative to improve soil moisture and increase nutrient availability to plants grown not only in drought conditions.