Livestock manure quantification and their plant nutrient contents for crop and forage production in Benin

Abstract

Livestock manure, feed biomass fed to animals that pass through digestive tract undigested and urine excreted from subsequent tissue metabolism, is conventionally termed as wastes. To optimize the use of their wastes for the purpose of agronomic processing or valorization, their availability and plant nutrients composition would be well understood. The use of reference values is a quick method of estimation. However, books on farm fertilizers generally offer only an average value that is not representative of the diversity of situations. The aim of this study was to (1) estimate the quantity of manures of cattle, sheep, goat, swine and poultry, (2) determine the physico-chemical characteristics and plant nutrient contents of these droppings and (3) identify the inter-relationships between the physical characteristics (pH, Electrical Conductibility (EC) and Dry Matter (DM)) and the most essential macronutrients (N, P and K). A multi-stage sampling technique was employed to select the herds or flocks for the survey. Accordingly, it was selected 5 departments, 3 communes per department and 2 herds or flock per commune. A total of 30 animal groups (herds or flocks) were investigated per species. Animal dung was sampling two times per months giving a total of 720 samples per species were collected over twelve months (January 1st to December 31st, 2015) to determine DM content, pH, EC, N, P, K, Ca, Mg and Na. The population of cattle, sheep, goat, swine and poultry of Benin in 2016 was reported to be 2.339; 0.915; 1.836; 0.466 and 20 million, respectively. Accordingly, the results of the study showed that, an amount of 1630600, 227800, 136900, 122400, 36500 tons DM of cattle manure, sheep dung, goat dung, swine dropping and of poultry excreta, respectively, are annually available in Benin. Physico-chemical and analyzes of these wastes showed significant differences (P˂0.05) between mineral compositions of these manure. Poultry droppings were richer in macronutrients than other animal manure (N = 11.7 ± 3.9, P = 5.6 ± 2.3, K = 7.6 ± 1.3, Ca = 15.2 ± 6.7 g/kg), followed by goat and sheep manure (N = 6.0 ± 3.7, P = 4.9 ± 3.9, K = 7.3 ± 3.3, Ca = 7.7 ± 3.8 g/kg and N = 6.7 ± 2.3, P = 4.4 ± 1.5, K = 7.7 ± 3.6, Ca = 7.8 ± 2.6 g/kg, respectively). Mean macronutrient compositions of swine droppings were: (N = 4.5 ± 2.0, P = 1.4 ± 0.8, K = 2.9 ± 0.8, Ca = 1.8 ± 0.9 g/kg). The animal manure that showed the lowest levels of these three macronutrients were those of cattle (N = 3.0 ± 0.6, P = 0.6 ± 0.1, K = 4.1 ± 0.9, Ca = 6.4 ± 3.1 g/kg). Correlations between physico-chemical properties (pH, EC, DM) and nutrient concentration showed that DM and EC be used to estimate nutrient (N, P and K) concentrations. The results vary widely depending on the source and type of dejection but they are a good basis for choosing rational and optimal soil fertilization for crop and forage productions.