Dry matter, root biomass and carbon as a function of crop rotation in a no-till system in Brazil

Authors: TANAKA, KATIUCA SUEKO - Sao Paulo State University (UNESP); MOMESSO MARQUES, LETUSA - Sao Paulo State University (UNESP); COCATTO, ISABELA - Sao Paulo State University (UNESP); FABRETTI, BEATIZ - Sao Paulo State University (UNESP); CRUSCIOL, CARLOS COSTA - Sao Paulo State University (UNESP); Franzluebbers, Alan

Submitted to: Abstract of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 10/3/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: One of the key concepts of sustainable conservation agriculture system is to keep the soil surface covered throughout the year. In tropical regions with irregular rainfall and dry winter, such as Brazilian Cerrado, cover crops in the off-season have large risk in growing a successful crop and the amount of plant residues produced is low. Another key is root biomass, which is a source of soil organic matter and it may improve soil structure. Therefore, choice of cover crop is essential for the sustainability of conservation agricultural system in tropical regions. We evaluated above-ground dry matter and root biomass in four different crop systems that were grown under no-till system since 2006. The treatments consisted of four production systems, varying by the type of crop during the dry-season (forage crop; second crop; cover crop and fallow). Introducing a cover crop or a second crop in the system increased plant residues by 38% and 23% over fallow, respectively. When a forage crop was used, plant residues more than doubled. Forage crop system presented greater root biomass in all depths (0-0.05; 0.05-0.1; 0.1-0.2; 0.2-0.4 and 0.4-0.6 m) than other systems. Green manure was the system that had lower root biomass than forage crop, fallow and second crop. Carbon concentration in root biomass (0-0.6 m) was greater in second crop and forage crop than cover crop and fallow. Roots and plant residues are an important source of carbon input to keep or increase organic matter. To enhance yield in a sustainable way, use of forage grass in the system was a great option for farmers to diversify their operations.

Technical Abstract: One of the key concepts of sustainable conservation agriculture system is to keep the soil surface covered throughout the year. In tropical regions with irregular rainfall and dry winter, such as Brazilian Cerrado, cover crops in the off-season have large risk in growing a successful crop and the amount of plant residues produced is low. Another key is root biomass, which is a source of soil organic matter and it may improve soil structure. Therefore, choice of cover crop is essential for the sustainability of conservation agricultural system in tropical regions. We evaluated above-ground dry matter and root biomass in four different crop systems that were grown under no-till system since 2006. The treatments consisted of four production systems, varying by the type of crop during the dry-season (forage crop; second crop; cover crop and fallow). Introducing a cover crop or a second crop in the system increased plant residues by 38% and 23% over fallow, respectively. When a forage crop was used, plant residues more than doubled. Forage crop system presented greater root biomass in all depths (0-0.05; 0.05-0.1; 0.1-0.2; 0.2-0.4 and 0.4-0.6 m) than other systems. Green manure was the system that had lower root biomass than forage crop, fallow and second crop. Carbon concentration in root biomass (0-0.6 m) was greater in second crop and forage crop than cover crop and fallow. Roots and plant residues are an important source of carbon input to keep or increase organic matter. To enhance yield in a sustainable way, use of forage grass in the system was a great option for farmers to diversify their operations.