Relationships between labile soil organic carbon fractions under different soil management systems

The study of labile carbon fractions (LCF) provides an understanding of the behavior of soil organic matter (SOM) under different soil management systems and cover crops. The aim of this study was to assess the effect of different soil management systems with respect to tillage, cover crop and phosphate fertilization on the amount of the LCF of SOM. Treatments consisted of conventional tillage (CT) and no-tillage (NT) with millet as the cover crop and a no-tillage system with velvet bean at two phosphorus dosages. Soil samples were collected and analyzed for organic carbon (OC), C oxidizable by KMnO4 (C-KMnO4), particulate OC (POC), microbial biomass carbon and light SOM in the 0.0-0.05, 0.05-0.10 and 0.10-0.20 m soil layers. The Carbon Management Index (CMI) was calculated to evaluate the impacts of soil management treatments on the quality of the SOM. The different LCFs are sensitive to different soil management systems, and there are significant correlations between them. C-KMnO4 is considered the best indicator of OC carbon lability. In the soil surface layers, the CT reduced the carbon content in all of the labile fractions of the SOM. The use of phosphorus led to the accumulation of OC and carbon in the different soil fractions regardless of the tillage system or cover crop. The application of phosphate fertilizer improved the ability of the NTsystem to promote soil quality, as assessed by the CMI.

Relationships between labile soil organic carbon fractions under different soil management systems

The study of labile carbon fractions (LCF) provides an understanding of the behavior of soil organic matter (SOM) under different soil management systems and cover crops. The aim of this study was to assess the effect of different soil management systems with respect to tillage, cover crop and phosphate fertilization on the amount of the LCF of SOM. Treatments consisted of conventional tillage (CT) and no-tillage (NT) with millet as the cover crop and a no-tillage system with velvet bean at two phosphorus dosages. Soil samples were collected and analyzed for organic carbon (OC), C oxidizable by KMnO4 (C-KMnO4), particulate OC (POC), microbial biomass carbon and light SOM in the 0.0-0.05, 0.05-0.10 and 0.10-0.20 m soil layers. The Carbon Management Index (CMI) was calculated to evaluate the impacts of soil management treatments on the quality of the SOM. The different LCFs are sensitive to different soil management systems, and there are significant correlations between them. C-KMnO4 is considered the best indicator of OC carbon lability. In the soil surface layers, the CT reduced the carbon content in all of the labile fractions of the SOM. The use of phosphorus led to the accumulation of OC and carbon in the different soil fractions regardless of the tillage system or cover crop. The application of phosphate fertilizer improved the ability of the NTsystem to promote soil quality, as assessed by the CMI.(AU)

Phosphorus fertilization in the sowing furrow and foliar as affecting the common beans grain yield / Adubação fosfatada no sulco e foliar afetando a produtividade de grãos do feijoeiro comum

Phosphorus (P) is an essential element in plant metabolism, and limiting the production of beans. One option would be through foliar fertilization, favoring the reduction of phosphate fertilizers in the soil, causing economic and environmental gains. However, this practice is still carried out without scientific basis, making it difficult to obtain reliable results. The aim of this study was to test the hypothesis that the foliar P application increases the efficiency of utilization of P from soil by bean. The trial was conducted for three consecutive years in a representative soil of the Cerrado in the winter season with supplemental irrigation. The experimental design was randomized blocks with four replicates in a factorial scheme 4 (rates of P applied in the soil) x 4 (rates of P applied foliar). The Increased in the rates of P applied to soil and foliar provided increased in the number pods m-2, grain yield and P content in the common bean plant. The highest grain yield (3,446 kg ha-1) was obtained with the combination of 120 kg ha-1 of P2O5 in the soil with 1662 g of P2O5 ha-1 foliar. The crop response to the application of P in the soil was increased with foliar application.(AU)

O fósforo (P) é um elemento essencial no metabolismo das plantas. Devido à elevada taxa de fixação do P em solos tropicais, o aproveitamento pela cultura varia de 5% a 25%. Uma opção seria fornecê-lo por meio da adubação foliar, favorecendo a redução da quantidade de adubos fosfatados aplicados via solo, gerando ganhos econômicos e ambientais. Entretanto, essa prática ainda é realizada sem embasamento cientifico, o que dificulta a obtenção de resultados confiáveis. O objetivo deste trabalho foi testar a hipótese de que a aplicação de P foliar aumenta a eficiência de utilização de P do solo pelo feijoeiro. O experimento foi realizado por três anos agrícolas consecutivos em solo representativo do Cerrado, em cultivo de inverno com irrigação suplementar. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições, em esquema fatorial 4 (doses de P no solo) x 4 (doses de P via foliar). O aumento das doses de P aplicadas via solo e foliar proporcionaram aumento do número vagens m-2, produtividade e teor de P na planta do feijoeiro comum. A maior produtividade do feijoeiro (3446 kg ha-1) foi obtida com a combinação de 120 kg ha-1 de P2O5 via solo com 1662 g de P2O5 ha-1 via foliar. A resposta da cultura à aplicação de P no solo é incrementada com a aplicação do nutriente via foliar.(AU)

Phosphorus fertilization in the sowing furrow and foliar as affecting the common beans grain yield / Adubação fosfatada no sulco e foliar afetando a produtividade de grãos do feijoeiro comum

Phosphorus (P) is an essential element in plant metabolism, and limiting the production of beans. One option would be through foliar fertilization, favoring the reduction of phosphate fertilizers in the soil, causing economic and environmental gains. However, this practice is still carried out without scientific basis, making it difficult to obtain reliable results. The aim of this study was to test the hypothesis that the foliar P application increases the efficiency of utilization of P from soil by bean. The trial was conducted for three consecutive years in a representative soil of the Cerrado in the winter season with supplemental irrigation. The experimental design was randomized blocks with four replicates in a factorial scheme 4 (rates of P applied in the soil) x 4 (rates of P applied foliar). The Increased in the rates of P applied to soil and foliar provided increased in the number pods m-2, grain yield and P content in the common bean plant. The highest grain yield (3,446 kg ha-1) was obtained with the combination of 120 kg ha-1 of P2O5 in the soil with 1662 g of P2O5 ha-1 foliar. The crop response to the application of P in the soil was increased with foliar application.

O fósforo (P) é um elemento essencial no metabolismo das plantas. Devido à elevada taxa de fixação do P em solos tropicais, o aproveitamento pela cultura varia de 5% a 25%. Uma opção seria fornecê-lo por meio da adubação foliar, favorecendo a redução da quantidade de adubos fosfatados aplicados via solo, gerando ganhos econômicos e ambientais. Entretanto, essa prática ainda é realizada sem embasamento cientifico, o que dificulta a obtenção de resultados confiáveis. O objetivo deste trabalho foi testar a hipótese de que a aplicação de P foliar aumenta a eficiência de utilização de P do solo pelo feijoeiro. O experimento foi realizado por três anos agrícolas consecutivos em solo representativo do Cerrado, em cultivo de inverno com irrigação suplementar. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições, em esquema fatorial 4 (doses de P no solo) x 4 (doses de P via foliar). O aumento das doses de P aplicadas via solo e foliar proporcionaram aumento do número vagens m-2, produtividade e teor de P na planta do feijoeiro comum. A maior produtividade do feijoeiro (3446 kg ha-1) foi obtida com a combinação de 120 kg ha-1 de P2O5 via solo com 1662 g de P2O5 ha-1 via foliar. A resposta da cultura à aplicação de P no solo é incrementada com a aplicação do nutriente via foliar.