Coverage period influences biomass and agricultural yield

Irrigated cultivation of cover crops for up to 105 days increased biomass production and soybean and common bean productivity in the Cerrado region. The management also improved soil chemical attributes after three years. Among the treatments, the Salud mix showed the best results for soybeans and increased nutrient availability.

The study evaluated nine cover crops and four growing seasons in Santo Antônio de Goiás, Goiás (doi 10.1002/cft2.70151). The researchers conducted the experiment during the growing seasons of 2022 to 2025, under center pivot irrigation and no-till systems. The annual sequence included cover crops, common beans, and soybeans.

Periods evaluated

The evaluated periods reached 60, 75, 90, and 105 days. To obtain these durations, the team sowed the cover crops 60, 45, 30, and 15 days after the soybean harvest. All received desiccation on the same date, 15 days before sowing the beans.

Biomass increased linearly with the increase in the time spent in the field. The cover crops produced 1.178 kilograms per hectare at 60 days and 6.309 kilograms per hectare at 105 days. This result represents an increase of more than five times between the two periods.

Higher production

Millet, Pennisetum glaucum, recorded the highest average biomass production, with 5.563 kilograms per hectare. The forage mix reached 5.259 kilograms per hectare. This mixture included Urochloa ruziziensis, Eleusine coracana, Pennisetum glaucum, and Sorghum bicolor.

Spontaneous vegetation showed the lowest average, with 3.134 kilograms per hectare. This result reinforces the importance of choosing species with the capacity for rapid growth and high straw production.

The effect of the planting period varied among the cover crops. Urochloa ruziziensis and the Salud mix showed strong biomass gain between 60 and 105 days. Black oat, Avena strigosa, and buckwheat, Fagopyrum esculentum, responded with less intensity. The data indicate the need to align the species with the time available between soybean harvest and bean planting.

Species gathered

The Salud mix brought together species of grasses, legumes, and brassicas. The composition included Vigna radiata, Pennisetum glaucum, Urochloa ruziziensis, Eleusine coracana, Raphanus sativus, Crotalaria ochroleuca, and Crambe koktebelica.

After three years, this consortium showed the highest levels of calcium, magnesium, phosphorus, sulfur, and soil organic matter compared to most isolated species. The treatment also achieved the highest cation exchange capacity.

The growing season influenced potassium, sulfur, iron, manganese, zinc, organic matter, cation exchange capacity, pH, and base saturation. Soil analysis was performed only once, at the end of the third year. Therefore, the results represent cumulative effects and do not allow for tracking annual changes.

Soybean response

Soybeans responded well to the cover crop used. The Salud mix yielded 4.973 kilograms per hectare. Millet reached 4.965 kilograms per hectare. Urochloa ruziziensis produced 4.897 kilograms per hectare.

Buckwheat showed the lowest soybean productivity, at 4.574 kilograms per hectare. Spontaneous vegetation reached 4.781 kilograms per hectare.

The longer period also benefited the oilseed. Productivity increased from 4.955 kilograms per hectare after 60 days of cover to 5.303 kilograms per hectare after 105 days. The gain reached 348 kilograms per hectare.

Bean response

Common bean, Phaseolus vulgaris, did not show a significant response to the species. However, the duration of the cover crops influenced the yield. Productivity increased from 2.064 kilograms per hectare at 60 days to 2.306 kilograms per hectare at 105 days. The 90-day period recorded 2.382 kilograms per hectare.

Researchers attribute the difference between soybeans and beans to the timing of nutrient release. Beans were planted immediately after desiccation. Soybeans were sown after the bean harvest, with most of the biomass already decomposing. This interval may have increased the oilseed's nutrient uptake.

The study did not evaluate costs or financial return. The results demonstrate agronomic gains from extending the irrigated cover period. Management for up to 105 days increased straw entry, improved soil attributes, and enhanced the performance of commercial crops.

The research was developed by scientists Adriano S. Nascente, Izabely VL Ferreira, Rafael B. Oliveira, Dennis RC Cruz, Natasha OC Monteiro, Victorya GM Souza, Edmilson JM Caetano, Aline CM Façanha, and Evandro I. Costa.