Nutrient Dynamics in Sandy Soil and Leaf Lettuce Following the Application of Urea and Urea-Hydrogen Peroxide Impregnated Co-Pyrolyzed Animal Manure and Bone Meal

Abstract

There is a paucity of data regarding the effect of nutrient-enriched biochar amendments on nutrient dynamics in both soil and crops. This is important because unlike pristine biochar, nutrient-enriched biochar is applied to the soil in minute quantities as large amounts may led to over application of the nutrients loaded in it. The current study examined the effects of both phosphorus- and nitrogen-enriched biochars on the dynamics of both macro and micronutrients in the sandy soil and leaf lettuce grown thereon. The phosphorus enrichment followed co-pyrolysis of animal manure (cow dung) with 25% and 50% bone meal (w/w), while the nitrogen enrichment was achieved by soaking the co-pyrolyzed biochar into urea and urea-hydrogen peroxide. The performances of the nutrient-enriched biochar were compared with the conventional amendment of urea and triple superphosphate (TSP) in the production of leaf lettuce over a period of two seasons in a pot experiment. The nutrient-enriched biochar amendments resulted into higher microbial biomass carbon and carbon to nitrogen ratios than the conventional amendment. The conventional amendment caused more phosphorus, potassium, and magnesium accumulations in the leaf lettuce than the nutrient-enriched biochar amendments. The nutrient-enriched biochar amendments led to more accumulations of nitrogen, calcium, and micronutrient elements in the leaf lettuce and availabilities of all the nutrient elements in the soil and thus, nutrient-enriched biochar acted as a reservoir that could provide nutrients to the growing lettuce beyond a single growing season.

Mixing Sodium-Chloride-Rich Food Waste Compost with Livestock Manure Composts Enhanced the Agronomic Performance of Leaf Lettuce

“…Another plausible explanation for the poor agronomic performance of the leaf lettuce grown on the conventional NPK amendment in comparison with the compost amendments is the inability of the sandy soil used in the present study to avail nutrients, especially N (leached), P (fixed), and micronutrients, to the growing leaf lettuce as demonstrated by Luyima et al [35]. The mixed composts produced from the amalgamations of FWC and livestock manure composts outperformed both the pure livestock manure composts and FWC up to the optimum mixing ratios, beyond which the agronomic performance of the lettuce decreased with increasing FWC in the mixture.…”

“…However, this line of argument may not be applicable to our study because leaf lettuce is a high-N-demanding crop (a heavy feeder). It is important to note, however, that both food waste and animal manures in both their raw and stabilised forms of biochar, compost, digestates, etc., are laden with both macro and micro crop nutrient elements [32][33][34][35] and can, therefore, adequately supply them to the growing crops.…”

Effects of Varying Rates of Nitrogen and Biochar pH on NH3 Emissions and Agronomic Performance of Chinese Cabbage (Brassica rapa ssp. pekinensis)

“…Nitrogen fertilizers are a rich source of ammonia (NH 3 ) which undergoes complicated reactions in the atmosphere to form secondary PM. NH 3 volatilizations from the fertilized agricultural soils mainly result from the low use efficiencies of the applied fertilizers by the crops grown [4]. With the expected increase in the use of nitrogen fertilizers in the future, especially in developing countries where the use efficiencies of the applied nitrogen fertilizers range between 30-50%, there is a high likelihood of heightened ammonia emissions [5].…”