Nitrogen use efficiency and soil chemical composition in small-scale dairy systems

Abstract

In dairy production systems, the efficient use of resources is required to guarantee its sustainability. Worldwide, the efficiency of feed utilization and its effects have been widely studied. However, few studies have quantified animal nitrogen use and its corresponding soil contribution in small-scale production systems. Therefore, this study aimed to determine the efficiency of feed utilization and quantify the soil chemical composition in small-scale production systems using two different feeding strategies. Twelve dairy farms were evaluated from May 2016 to April 2017. Data analysis was performed using an ANOVA following a completely randomized model and using feeding strategies as treatment. Regarding the feeding systems' characteristics, significant differences (P < 0.05) were only observed in land surface and land used to produce mixed-grass and corn. Nitrogen (N) input and output in dairy cattle were significantly different (P < 0.05) for crude protein intake. The highest results were observed in grazing feeding systems. The cut and carry strategies excreted 71% of the consumed N in the manure; grazing strategies excreted 72%. The efficiency of feed utilization (EFU) is low; only 19% of the consumed N is recovered during milk production. As for the soil chemical composition, significant differences (P < 0.05) were observed in the percentage of total N and the carbon to nitrogen (C:N) ratio. The remaining components behaved similarly in both feeding systems. Systems that include crops and livestock can positively change the biophysical and socioeconomic dynamics of agricultural systems.