Sustainable intensification alternatives for agricultural-livestock systems based on rotations and contrasting livestock strategies

Doctoral thesis abstract

Resumo

Sustainable intensification (SI) of production systems aims to increase yields without compromising the health of ecosystems. Integrated crop-livestock systems have been proposed as an SI alternative. Crop-pasture rotations are part of these systems and involve a pasture phase included in the crop sequence. The main reasons for including pastures in cropping systems are the low productivity of natural pastures and the increased crop yields after a pasture phase. The objective was to evaluate multidimensionally alternatives for intensifying crop-livestock systems for the period from May 2019 to April 2022, using information obtained from the long-term Palo a Pique experiment by INIA Treinta y Tres. The evaluated systems were CC (continuous cropping), SR (two years of CC, two years of pastures), LR (two years of CC, four years of pastures) and FR (continuous pasture with fescue). Live weight (LW) production was higher in CC and SR (426 and 418 kg LW/ha) than in LR (369 kg LW/ha) and FR (310 kg LW/ha). Grain production was 10%, 16% and 9% lower in soybean, wheat and sorghum in CC. The greenhouse gas (GHG) emission estimates were 11.3, 11.8, 11.8 and 16.4 kg CO2-eq/kg of LW produced for CC, SR, LR and FR. The average emissions of crops were 1.23, 0.53 and 0.52 kg CO2-eq/kg for soybean, wheat and oat. The NUE of the system was 43.4%, 28.1%, 29.3% and 5.5% for CC, SR, LR and FR. The N balance at the system level was 4.9±1.52, 41±3.1, 29±2.2 and 64±3.5 for CC, SR, LR and FR. On average, the gross margin was 285, 200, 181 and 197 US$/ha for LR, SR, CC and FR. Crop-livestock systems with a pasture phase (short or long) in the rotation can improve various sustainability indicators.