“…one of the biggest challenges for tropical agriculture and the no-tillage system today is the production of biomass in quantity, uniformity and with permanence on the soil surface…”
Vagner Nascimento holds a degree in agronomy, a master’s degree in phytotechnics, a doctorate, and a postdoctoral degree in phytotechnics and soil science at Universidade Estadual Paulista (Unesp), from the Ilha Solteira campus.
Nascimento is a professor at Unesp, on the Dracena campus, working in phytotechnics, agricultural production systems, cover crops, among other areas.
AgriBrasilis – What is the importance of covering the soil?
Vagner Nascimento – The amount of coverage (tonne/hectare) uniformly and permanently on the soil’s surface with plant residues (straw) in the various agricultural production systems is essential from an economic, social, and environmental perspective. Also essential is a quality no-till system, with a focus on sustainability, mainly in tropical regions where rates of decomposition of plant residues are accelerated in relation to regions with a temperate climate.
Soil coverage is used to improve the soil’s physical, chemical, and biological conditions. In addition, it is considered a conservationist practice by which plant species are cultivated and then incorporated or maintained on the soil’s surface, at a certain phenological stage, to ensure or increase the soil’s productive capacity.
The main benefits of cover crops are related to the protection of soil against water and wind erosion; keeping high water infiltration rates; promoting a continuous supply of dry plant mass; increasing water storage capacity in the soil; effectively mobilizing and recycling nutrients; promoting supply of nitrogen; reducing weed populations; providing favorable environmental conditions for life in the soil; providing beneficial allelopathy; storing carbon in the soil; attenuating and controlling thermal oscillations; recovering degraded soils; solubilizing phosphorus; reducing nutrient leaching; increasing cation exchange capacity and the stability of soil aggregates; assisting in fixing compacting of the soil; assisting in the management of nematodes and root pathogens; improving the efficiency of mineral fertilizers and human and animal food.
AgriBrasilis – What are the main cover crop species in agriculture?
Vagner Nascimento – The main families and species of cover crops used belong to the Fabaceae (Crotalaria spp., velvet bean, pigeon pea, soybean, jack bean, lablab, Stylosanthes spp., common vetch, forage pea, lupines, etc.), Poaceae (millet, corn, sorghum, wheat, rye, triticale, barley, oats, annual ryegrass, annual and perennial tropical forages of the genera Urochloa, Megathyrsus spp., sudangrass, Eleusine coracana, and Andropogon L.), Cruciferous plants (radish, rapeseed, and canola); Asteraceae (sunflower); Polygonaceae (buckwheat); Caryophyllaceae (Spergula arvensis) and Linaceae (flax).
The trend nowadays is towards intercropping (Crotalaria spp. + Urochloa spp., Crotalaria spp + millet and sorghum + Urochloa spp.) and combinations of different species and families.
In this sense, the main characteristics when choosing species, be it for single planting or intercropping, are: high dry biomass yield; production of seeds that are easy to obtain and harvest; physiological cycle compatible with commercial crops; low susceptibility to diseases and pests; deep rooting and branching; aluminum tolerance and soil acidity; efficiency in nutrient extraction and cycling; high atmospheric nitrogen fixation; resistance/tolerance to water stress; efficiency in the management of weeds and nematodes, as well as the promotion of increments in cultivation yields in succession, rotation, and intercropping.
AgriBrasilis – What are the fundamental aspects in recommending land cover species in different production systems?
Vagner Nascimento – Main aspects to consider when recommending land cover species are: 1) the area’s history (previous plants and soil fertilization); 2) adaptation of plants to the climate and soil of the region; 3) the production system adopted on the farm; 4) non-interference in the agricultural activities of the farm; 5) minimal financial cost; 6) availability of seeds in the market and affordable price; 7) high productivity of dry biomass; 8) ease of handling (mechanical and chemical) of plant residues; 9) the farmer’s preference.