Effect of Liquid Digestate on Agricultural Soil – I: Growth Dynamics of Zea mays Plant

The study was designed to model the effect of liquid digestate on growth dynamics of Zea mays plant. Maize seeds were subjected to various concentrations of liquid digestate (between 0% and 72%) using One-Factor Response Design with a total of ten (10) runs in 10L-capacity plastic pots containing 10kg of loamy soil. One set of experimental runs were treated with one-time application of the corresponding digestate concentration (OTDA). Another set of experimental runs were treated with two-time application of the corresponding digestate concentration (TTDA). The first application of the liquid digestate (for OTDA and TTDA) was conducted two weeks after sowing while the second application (for TTDA alone) was conducted three weeks after the first application. The height of maize plant in all set-ups was monitored for a period of 70 days. After the 70-day period, the plants were harvested for biomass estimation. In the soil set-ups treated with OTDA, crop growth rate (1.077cm/day) and biomass yield (22.37g/kg of digestate) of Zea mays plant peaked with 48% digestate after 70 days. In the soil set-ups treated TTDA, crop growth rate (1.321cm/day) and biomass yield (29.95g/kg) of Zea mays plant peaked with 72% digestate after the same period. Optimum response generated for the crop growth rate of Zea mays plant was approximately 1.038 cm/day with a standard error of 0.014 for the OTDA treatment and 1.165cm/day and a standard error of 0.006 for the TTDA treatment at digestate concentration of 50% with a desirability of 0.928 respectively. Optimum response generated for biomass yield of the Zea mays plant was approximately 22.488 (g/kg) with a standard error of 0.621 for the OTDA treatment and 27.292 (g/kg) with a standard error of 0.399 for the TTDA treatment at digestate concentration of approximately 47.1% and a desirability of 0.930 respectively. The result suggests that the TTDA treatment method may have enhanced the growth of the maize plant better than the OTDA treatment method.