Cover crop mixtures in no-tillage systems: interaction between species and intercrop with corn

• Grant number: 21/13960-9
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2023
• End date: September 30, 2024
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Paulo Mazzafera
• Grantee: João Leonardo Corte Baptistella
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Conservationist production systems, such as no-tillage system (NT), represent a sustainable way to produce food, as long as its three principles are attained: (i) no soil tillage; (ii) permanent soil cover either as plant residues or living plants; and (iii) crop rotation. However, the way NT is done in Brazil, those principles are not always attained and problems such as soil compaction, low soil cover retention and low biodiversity. There well succeeded intercrops, like corn and Urochloa or Megathyrsus maximum, that provide good soil cover, as well as other benefits - better soil structure, nutrient cycling, and carbon sequestration, for example. On the other hand, there are several cover crop species that are feasible to be used in crop rotation in NT and cover crop mixtures are being empirically adopted by farmers. Although this practice can provide biodiversity to the system, we do not know which species are dominant and which are the real benefits when compared to the corn-grasses intercrop. In other terms, there is no criteria to this practice other than biodiversity. Inclusion of cover crops needs to have a criterion and attain the principles of NT, as well as providing multiple benefits to the system and be more advantageous to the farmer than the ordinary management. "Bio-tillage" aims at introducing perennial crops, with diverse, deep, and thick taproots with high decomposition rates. Using bio-tillage as criteria, plants are chosen based on the form and function of its roots, attaining NT principles and at the same time, providing several benefits to the system. In this context, our premise is that Urochloa and M. maximus are perennial crops that already provide benefits to NT but may benefit and be potentialized by the presence of other cover crops. Based on the bio-tillage criteria, we chose Crotalaria spectabilis Roth and Raphanus sativus L. to compose the mixtures with the grasses. The aim of this project is to study the judicious introduction of cover crops mixtures compose by grasses (Urochloa ruziziensis or M. maximum cv Mombaça), Crotalaria spectabilis e Raphanus sativus L. assessing soil quality (biological, chemical and physical), soil cover, biomass production, plant residue composition, as well as the ecological interaction between species and the feasibility of intercropping these mixtures with corn in the second season. We have designed three experiments to understand ecological interactions between plants in mixtures and the benefits provided to NT. In the first two experiments, we focused on these interactions and benefits of cover crops mixtures, in filed conditions and in rhizotrons, where we can take a closer look at the root system and plant residue recalcitrance. Next, we intend to study the feasibility of intercropping these mixtures with corn on the second season and compare it to the already successful corn-grass intercrop.