Phosphate Fertilization Without Pasture Burning Increase Biomass Productivity and Reduce Carbon Loss

Abstract

Objective: In this work we evaluate the phosphorus fertilization without burning on the biomass productivity and the reduction of carbon loss from the pasture of Brachiaria brizantha in the Brazilian Amazon. Theoretical Framework: Brachiaria brizantha is the main cultivated pasture species in Brazil. The overgrazing and no nutrient replenishment in addition to the periodical burnings are the trigger factors of a gradual degradation since the 70’s in the Amazon. That fact suggests the need for research solutions to eliminate the use of this practice for pasture management. Method: A field experiment was carried out from September to November 2015 in a completely randomized blocks design. The treatments consisted of unburned pasture treated with 0, 25, 100 and 200 kg ha-1 of phosphorus compared to the pasture burning, with 4 blocks and 20 experimental plots. The experimental plots treated with phosphorus received agronomic doses of potassium and nitrogen applied on the soil surface. After applying the treatments, including the burning, the pasture was desiccated in order to homogenize the plant emergence and growth after the period without rain from July to September. Results and Discussion: The soil fertility attributes, components of biomass productivity, partial carbon stocks and the partial carbon retained in the pasture (not lost as carbon dioxide) were quantified at 56 days after the beggining of the experimental period. In comparison to the pasture burning, the treatments alter the soil phosphorus availability and, as a result, increase the partial biomass productivity and its carbon content, reducing the loss of carbon dioxide to the atmosphere. Research Implications: The practical and theoretical implications of this research are discussed, providing insights into how the results can be applied or influence practices in the field of pasture management without fire using. These implications could encompass on how to apply and how much of an alternative phosphate must be applied to the soil in order to supply phosphorus for B. brizantha instead of using fire as a strategy of pasture management. Originality/Value: This study contributes to the literature by highlighting the superiority of phosphorus application from alternative source allied to N and K fertilization compared to the pasture burning practice in the Southwestern Amazon. This innovative approach can be used as a base for new researches and applied in the level of cattle farmers.