Carbon indices to assess quality of management systems in a Subtropical Acrisol

Management systems to improve soil quality are essential for agricultural and environmental sustainability. We assessed the quality of soil management systems applied to a subtropical Acrisol in terms of the carbon management index (CMI), the stratification ratio for total organic carbon (SR-TOC) and light fraction of organic matter (SR-LF). In addition, we examined their relationship to chemical, physical and biological soil quality indicators, as well as to maize yield. The study was conducted on a long-term experiment (18 years) in southern Brazil involving two different systems [no tillage (NT) and conventional tillage (CT)], two cropping systems [black oat/maize (O/M) and black oat + vetch/maize + cowpea (OV/MC)] and two nitrogen fertilizer rates for maize (0 and 180 kg ha–1). Based on the three indices, the best managements for soil quality comprised NT (50-212 % better than CT), legume cover crops (10-47 % better than O/M) and N fertilization (8-33 % better than no fertilizer). All three indices proved accurate to assess the impact of soil management systems, especially SR-LF, which showed increased sensitivity and close relationships with chemical, physical and biological soil quality indicators. On the other hand, a poor relationship was observed between soil C indices and maize yield, which was improved only by legume cover crops and N fertilization. The results showed that the association of no-till system to an abundant supply of crop residues is key to ensure high soil quality and crop yields in humid subtropical regions.

Carbon indices to assess quality of management systems in a Subtropical Acrisol

Management systems to improve soil quality are essential for agricultural and environmental sustainability. We assessed the quality of soil management systems applied to a subtropical Acrisol in terms of the carbon management index (CMI), the stratification ratio for total organic carbon (SR-TOC) and light fraction of organic matter (SR-LF). In addition, we examined their relationship to chemical, physical and biological soil quality indicators, as well as to maize yield. The study was conducted on a long-term experiment (18 years) in southern Brazil involving two different systems [no tillage (NT) and conventional tillage (CT)], two cropping systems [black oat/maize (O/M) and black oat + vetch/maize + cowpea (OV/MC)] and two nitrogen fertilizer rates for maize (0 and 180 kg ha–1). Based on the three indices, the best managements for soil quality comprised NT (50-212 % better than CT), legume cover crops (10-47 % better than O/M) and N fertilization (8-33 % better than no fertilizer). All three indices proved accurate to assess the impact of soil management systems, especially SR-LF, which showed increased sensitivity and close relationships with chemical, physical and biological soil quality indicators. On the other hand, a poor relationship was observed between soil C indices and maize yield, which was improved only by legume cover crops and N fertilization. The results showed that the association of no-till system to an abundant supply of crop residues is key to ensure high soil quality and crop yields in humid subtropical regions.(AU)

Canopy cover, biomass production and nutrient accumulation by coper crops / Cobertura do solo, produção de biomassa e acúmulo de nutrientes por plantas de cobertura

The use of cover crops is an important strategy for maintaining the productive capacity of agricultural land. This research aimed to determine the soil coverage, biomass production and accumulation of N, P, K, Ca and Mg in plant tissue of different species of cover crops on the southern plateau of Santa Catarina, Brazil. The experiment was conducted in a Humic Cambisol (Inceptisol) with the following treatments: i) BO - black oat (Avena strigosa); ii) WR - wild radish (Raphanus sativus L.); iii) CV - common vetch (Vicia sativa); iv) IS - intercropping of the three species; and v) WF - winter fallow with spontaneous vegetation. The use of cover crops has potential for high biomass production, canopy cover and nutrient accumulation by plant tissue, higher than winter fallow. In the early stage of plant development the highest growth rates and soil coverage occur in WR and IS, while at the end are higher in CV and IS. The crops of BO, CV and IS produce large amounts of dry shoot mass and BO produces greater dry root mass. In general, the CV and IS treatments and the shoot accumulate greater amounts of nutrients in plant tissue as compared to other treatments and the roots, respectively.(AU)

A utilização de plantas de cobertura do solo é importante estratégia para manutenção da capacidade produtiva de áreas agrícolas. A pesquisa objetivou determinar a cobertura do solo, a produção de fitomassa e o acúmulo de N, P, K, Ca e Mg no tecido vegetal de diferentes espécies de plantas de cobertura no Planalto Sul Catarinense. O experimento foi conduzido em um Cambissolo Húmico e foram avaliados os tratamentos: i) AP - aveia preta (Avena strigosa); ii) NF - nabo forrageiro (Raphanus sativus L.); iii) EC - ervilhaca comum (Vicia sativa); iv) CE - consórcio das três espécies; e v) PO - pousio com vegetação espontânea. O uso de plantas de cobertura tem potencial para alta produção de biomassa, cobertura pelo dossel e acúmulo de nutrientes pelo tecido vegetal, superior ao pousio de inverno. No início do desenvolvimento vegetal maior taxa de crescimento e cobertura do solo ocorrem em NF e CE, enquanto ao final destacam-se EC e CE. Os cultivos de AP, EC e CE produzem maiores quantidades de massa seca de parte aérea e o de AP produz maior massa de raízes. No geral, os tratamentos EC e CE e a parte aérea das plantas acumulam mais nutrientes no tecido vegetal em comparação aos demais tratamentos e as raízes, respectivamente.(AU)

Canopy cover, biomass production and nutrient accumulation by coper crops / Cobertura do solo, produção de biomassa e acúmulo de nutrientes por plantas de cobertura

The use of cover crops is an important strategy for maintaining the productive capacity of agricultural land. This research aimed to determine the soil coverage, biomass production and accumulation of N, P, K, Ca and Mg in plant tissue of different species of cover crops on the southern plateau of Santa Catarina, Brazil. The experiment was conducted in a Humic Cambisol (Inceptisol) with the following treatments: i) BO - black oat (Avena strigosa); ii) WR - wild radish (Raphanus sativus L.); iii) CV - common vetch (Vicia sativa); iv) IS - intercropping of the three species; and v) WF - winter fallow with spontaneous vegetation. The use of cover crops has potential for high biomass production, canopy cover and nutrient accumulation by plant tissue, higher than winter fallow. In the early stage of plant development the highest growth rates and soil coverage occur in WR and IS, while at the end are higher in CV and IS. The crops of BO, CV and IS produce large amounts of dry shoot mass and BO produces greater dry root mass. In general, the CV and IS treatments and the shoot accumulate greater amounts of nutrients in plant tissue as compared to other treatments and the roots, respectively.

A utilização de plantas de cobertura do solo é importante estratégia para manutenção da capacidade produtiva de áreas agrícolas. A pesquisa objetivou determinar a cobertura do solo, a produção de fitomassa e o acúmulo de N, P, K, Ca e Mg no tecido vegetal de diferentes espécies de plantas de cobertura no Planalto Sul Catarinense. O experimento foi conduzido em um Cambissolo Húmico e foram avaliados os tratamentos: i) AP - aveia preta (Avena strigosa); ii) NF - nabo forrageiro (Raphanus sativus L.); iii) EC - ervilhaca comum (Vicia sativa); iv) CE - consórcio das três espécies; e v) PO - pousio com vegetação espontânea. O uso de plantas de cobertura tem potencial para alta produção de biomassa, cobertura pelo dossel e acúmulo de nutrientes pelo tecido vegetal, superior ao pousio de inverno. No início do desenvolvimento vegetal maior taxa de crescimento e cobertura do solo ocorrem em NF e CE, enquanto ao final destacam-se EC e CE. Os cultivos de AP, EC e CE produzem maiores quantidades de massa seca de parte aérea e o de AP produz maior massa de raízes. No geral, os tratamentos EC e CE e a parte aérea das plantas acumulam mais nutrientes no tecido vegetal em comparação aos demais tratamentos e as raízes, respectivamente.