EFFECT OF BIOCHAR AND POULTRY MANURE ON SOIL PRODUCTIVITY AND PERFORMANCE OF ROSELLE (HIBISCUS SABDARIFFA L.)

Abstract

The challenges of food security in sub-Sahara Africa and the entire world have effects on the population increase and these have placed enormous pressure on lands to produce more food. Solving this challenge could be a tall order due to soil fertility depletion and increasing soil degradation, the need to produce food and agricultural crops with lower environmental footprint, while also dealing with climate change problems. Biochar has been shown to improve soil fertility, sequester carbon and potentially solve food security challenge. However, studies on its combination with other non pyrolized organic waste such as poultry manure and effect on soil properties and crop yield are scanty. This study investigated whether biochar derived from sawdust and poultry manure applied solely under different rates or combined can improve soil physical and chemical properties of degraded medium textured Alfisol in southwestern Nigeria, and how this in turn affects Roselle plant (Hibiscus sabdariffa L.) performance. A factorial field experiment was set up in a randomized complete block design (RCBD) in which different organic amendments: biochar, poultry manure and biochar + poultry manure were applied at three rates; 0, 2 and 5 t ha-1. Soil chemical properties (pH, organic carbon, N, P, K, Ca, Mg and CEC) of the soil were significantly affected by biochar, poultry manure application, rate of biochar, and poultry manure application and the interaction between biochar and poultry manure and rates of its application. Results obtained from this study showed that the application of 2 t ha-1and 5 t ha-1 significantly (P < 0.05) improved Roselle growth and yield compared to the control. However, critical examination of the differences arising from the application of 2 t ha-1and 5 t ha-1 of soil amendments revealed that no significant variation in growth and yield parameters could accrued to either. This suggests that application of a lower rate of soil amendment, i.e. 2 t ha-1, is economical to farmers, environment friendly and good for plant and soil health. Generally, soil fertility was maintained by the application of poultry manure and biochar compared to the control. This shows that there were significant interactions between biochar and poultry manure and rates of application on roselle growth and yield. Poultry manure + biochar at 5 t ha-1 recorded the highest plant height at 6, 8 and 10 WAP; biochar application at 2 t ha-1 recorded the highest number of leaves at 6, 8 and 10 WAP while biochar application at 5 t ha-1 recorded the highest stem girth at 6, 8 and 10 WAP. Roselle with 2 t ha-1 of biochar application, 5 t ha-1 of biochar application, 5 t ha-1 of biochar application, 2 t ha-1 of poultry manure application and 5 t ha-1 of biochar recorded the highest fresh weight, number of calyxes, weight of calyxes, number of seeds and weight of fruits of Roselle respectively. In conclusion, these results show the importance of the application of biochar and poultry manure as soil amendment for Roselle production.