Organic Carbon and Total Nitrogen in the Densimetric Fractions of Organic Matter Under Different Soil Management

Abstract

-The evaluation of land use and management by the measurement of soil organic matter and its fractions has gained attention since it helps in the understanding of the dynamics of their contribution to soil productivity, especially in tropical environments. This study was conducted in the municipality of Colorado do Oeste, state of Rondônia, Brazil and its aim was to determinethe quantity of organic carbon and total nitrogen in the light and heavy fractions of organic matter in the surface layers of a typic hapludalf under different land use systems: Native Forest: open evergreen forest, reference environment; Agroforestry System 1: teak (Tectona grandis LF) and kudzu (Pueraria montana); Agroforestry System 2: coffee (Coffea canephora), marandu palisade grass (Brachiaria brizantha cv. Marandu), "pinho cuiabano" (Parkia multijuga), teak and kudzu.; Agroforestry System 3: teak and cocoa (Theobroma cacao); Silvopasture System: teak, cocoa and marandu palisade grass; and Extensive Grazing System: marandu palisade grass. The experimental design was a randomized block in split-split plots (use systems versus soil layers of 0-0.05 and 0.05-0.10 m) with three replications. The results showed that relative to Native Forest, the Agroforestry System 2 had equal-and greater amounts of organic carbon and total nitrogen respectively (light and heavy fractions) in the soil organic matter, with the light fraction being responsible for storage of approximately 45% and 70% of the organic carbon and total nitrogen, respectively. Therefore, the light densimetric fraction proved to be useful in the early identification of the general decline of the soil organic matter in the land use systems evaluated.Keywords: Silvopasture system. Agroforestry system. Forest cultivation. CARBONO ORGÂNICO E NITROGÊNIO TOTAL NAS FRAÇÕES DENSIMÉTRICAS DA MATÉRIA ORGÂNICA SOB DIFERENTES MANEJOS DO SOLORESUMO -A avaliação de sistemas de uso e manejo dos solos por meio da matéria orgânica e seus compartimentos tem ganhado apelo, pois ajuda a entender a dinâmica do seu aporte, principalmente em ambientes tropicais. Objetivou-se neste trabalho determinar, no município de Colorado do Oeste, Rondônia, a alteração do carbono orgânico e nitrogênio total nas frações leve e pesada da matéria orgânica da camada superficial de um ARGISSOLO VERMELHO-AMARELO Eutrófico típico sob diferentes usos do solo: Floresta nativa (FN): Floresta Ombrófila Aberta, como ambiente referência; sistema agroflorestal 1: teca (Tectona grandis L. F.) e kudzu (Pueraria montana); sistema agroflorestal 2: café (Coffea canephora), pastagem (Brachiaria brizantha cv. Marandu), pinho cuiabano (Parkia multijuca), teca e kudzu; Sistema agrossilvopastoril: Teca, cacau (Theobroma cacao) e pastagem; sistema agroflorestal 3: Teca e cacau; pastagem extensiva: (B. brizantha cv. Marandu). O delineamento empregado foi o de blocos casualizados em esquema de parcelas subdivididas (diferentes coberturas vegetais versus camadas de solo à 0-0,05 e a 0,05-0,10 m) com três repetições. Verificou-se que:...

Assessment of Soil Quality Index Along Hydrosequence in Grain Crops Growing Areas of Najaf and Diwaniya Governorates of Iraq

“…As for the lowest total nitrogen content that appeared in the fourteenth pedon, shown the same decrease in the content of organic matter was accompanied by the increase of one of them accompanied by a relative increase in the other, as the total nitrogen content increased with the increase in the content of organic matter, and this is also confirmed by many researchers that there is a direct relationship between the organic matter content and total nitrogen content in the soil (Prado et al, 2016;Mazzoncini et al, 2011; The previous table (3) shows the values of available nitrogen, phosphorous, and potassium in the soil, as the highest value of available nitrogen reached 77.00 mg. Kg -1 in the tenth pedon of the second transects, which is located at the end of the hydrosequences of the second transects, as the reason for this may be due to the fact that the available nitrogen is able to move with irrigation water or ground water and may be washed to lower areas with water courses in general as a result of irrigation or rainwater operations. The higher areas of the hydrosequences also showed a relatively low content of the available nitrogen and this is consistent with what Honeycutt et al, 1990found., Senthilkumar et al, 2009Ogeh and Ukodo, 2012. As for the available phosphorous in the soil presented in Table (3), it indicates that its highest value was located in the fifth pedon, which is located at the top of the hydrosequences of the first transects, also the thirteenth pedon in the second transects is a high value of available phosphorus, and the reason for this may be due to the increase in rural activity in the study area as well as to the severe agricultural conditions, since the soils of this pedon are planted with many crops such as wheat, barley, Medics.…”

Ecosystem Services from Ecological Agroforestry in Brazil: A Systematic Map of Scientific Evidence

“…Another share of these studies inferred that the positive effects of AF on soils were related to species structure and richness. By comparing different types of AF (with a different number of species) and natural vegetation as a control, these studies found better contributions for soil quality from the most diverse and rich AF than from the least diverse and rich ones [87,91,[98][99][100][101].…”