Soil Structural Quality and Relationships With Root Properties in Single and Integrated Farming Systems

Single farming systems (SFS) such as monocultures may negatively affect soil structural quality. This study tested the hypothesis that integrated farming systems (IFS), i.e., the combination of cropping and forestry and/or livestock farming, improves soil structural quality, root development and soil organic carbon. An experimental area was set up in 2012 at the Canguiri experimental farm belonging to the Federal University of Parana, Southern Brazil. The soils are predominantly Ferralsols. The experimental treatments representing different farming systems, organized in a random block design with three replicates, were: Forestry (F), Conventional Crop Production (C), Livestock (L), and integrated Crop-Forestry (CF), Crop-Livestock (CL), Livestock-Forestry (LF), and Crop-Livestock-Forestry (CLF). In situ measurements and sampling were carried out in the 0-0.3 m layer during summer 2019/20, and included soil penetration resistance (PR), soil structural quality based on visual evaluation of soil structure (Sq(VESS) scores), root length (RL), root volume (RV) and soil organic carbon content (SOC). Soil structural quality, penetration resistance, root length and volume, and SOC varied between farming systems, but no significant differences were found between single (C, L, F) and integrated farming systems (CF, CL, LF, CLF). The single system Forestry (F) and the integrated systems including forestry (LF, CF, CLF) tended to have higher Sq(VESS) scores, i.e. poorer soil structural quality, and higher PR, which we associate with the generally drier soil conditions that are due to higher soil water uptake and higher interception and reduce the frequency of wetting-drying cycles. Roots were concentrated in the shallow soil layer (0-0.1 m depth), and this was especially pronounced in the Crop (C) single farming system. Based on the measured values, our results suggest an acceptable soil structural quality in all farming systems. Our data revealed strong, significant relationships between soil structural quality, penetration resistance, root growth and SOC, demonstrating that improvements in soil structure results in lower soil penetration resistance, higher root volumes and higher SOC, and vice versa. Soil PR was positively correlated with Sq(VESS) (R-2 = 0.84), indicating that better soil structural quality resulted in lower soil mechanical resistance. This, in turn, increased root length and volume, which increases carbon input to soil and therefore increases SOC in the long run

Estrutura do solo em sistemas agropecuários e sua relação em parâmetros radiculares

Orientadora: Profª Drª Karina Maria Vieira Cavalieri-PolizeliCo-orientadora: Profª Drª Fabiane Machado VezzaniDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Ciência do Solo. Defesa : Curitiba, 28/05/2021Inclui referências: p. 50-58Resumo: A falta de adoção de práticas conservacionistas e o uso de monocultivo influenciam negativamente na qualidade do solo, sendo assim os sistemas integrados de produção agropecuária vêm sendo adotados como parte da solução para produzir, recuperar e conservar os solos e os organismos vivos. Diante do exposto, o presente estudo teve como objetivos i) determinar indicadores da qualidade estrutural do solo em sistemas de produção agropecuária; ii) avaliar o desenvolvimento de raízes em cada sistema e relacionar atributos de raízes com os indicadores de qualidade estrutural do solo. O estudo faz parte de um experimento de longa duração iniciado em 2012 e, foi desenvolvido na Fazenda Experimental Canguiri da Universidade Federal do Paraná, no município de Pinhais-PR. Os solos compreendem Latossolos e Cambissolos em menor proporção. Os tratamentos avaliados foram: Floresta plantada (F), Lavoura (L), Pecuária (P), Lavoura-Floresta (LF), Lavoura-Pecuária (LP), Pecuária-Floresta (PF), e Lavoura-Pecuária-Floresta (LPF). O delineamento experimental foi blocos ao acaso, estudando três camadas de solo 0 – 0,10, 0,10 – 0,20 e 0,20 – 0,30 m. Determinou-se a resistência do solo à penetração (RP), a Avalição Visual da Estrutura do Solo (VESS) e parâmetros radiculares tais como: comprimento radicular (CR), volume radicular (VR), massa seca de raízes (MSR), área superficial específica (ASE), classes de diâmetros das raízes bem como o teor de carbono orgânico total (COT). Os resultados indicaram diferença estatística para os valores médios do VESS entre os tratamentos. O tratamento F apresentou a média maior (3,33), diferindo de todos os tratamentos, porém os resultados encontrados apontam para qualidade estrutural do solo (Qe) aceitável (Qe<3) da estrutura do solo. Similarmente, a RP apresentou diferenças estatísticas do tratamento F em relação aos demais, a maior média de RP foi de 3 MPa. As médias do COT variaram de 32 a 55 g kg-1 não diferindo estatisticamente entre os sistemas de produção. A maior concentração de raízes foi observada na camada de 0 - 0,10 m, e essa concentração reduziu com o aumento da profundidade. Assim sendo, foram obtidas relações significativas entre as variáveis. A RP correlacionou positivamente com o VESS e ambas se correlacionaram negativamente com o COT e com as variáveis das raízes, sendo que o aumento do VESS explicou 89% da redução do VR, 82% do CR e cerca de 61 % da redução do COT. Enquanto a RP explicou em torno de 70 a redução do VR e CR. O aumento da RP foi positivamente correlacionado com o VESS (R2=0,84). Entre os sistemas avaliados o F foi o que apresentou valores mais elevados tanto de RP quanto de VESS, porém, assim como todos os sistemas, apresentou qualidade de estrutura aceitável (Qe<3) para o desenvolvimento dos componentes produtivos. Assim, os diferentes sistemas de produção apresentaram adequada qualidade da estrutura do solo, indicando que manejo do solo praticado nos sistemas de produção agropecuária está sendo eficiente em proporcionar condições adequadas de solo para as culturas.Abstract: The lack of adoption of conservation practices and the use of monoculture negatively influences soil quality, then integrated systems of agricultural production have been adopted as part of the solution to produce, recover and conserve soils and organisms. The present study aimed to determine soil penetration resistance (RP) and Visual Evaluation of Soil Structure (VESS) as indicators of soil structural quality in integrated systems of agricultural production; to evaluate the development of roots in each system and to relate root attributes with soil total organic carbon, with PR and VESS. The study is part of a long-term experiment, started in 2012 and was carried out at the Canguiri farm experimental station belong to Federal University of Paraná, at the municipality of Pinhais. The soil is classified as an oxisol with the presence of Cambisol. The treatments evaluated are: Planted Forest (F), Tillage (T), Livestock (L), Till-Forest (TF), Livestock Crop (LC), Livestock-Forest (LF), and Crop-Livestock-Forest (CLF). The experimental design adopted was randomized blocks, in a split plot scheme with 4 replicates per experimental unit. PR, VESS and root parameters such as; root length (CR), root volume (VR), root dry mass (MSR), specific surface area (ASE), four classes of root diameters as well as total organic carbon content (COT). The samples were collected in the following layers: 0 - 0.10, 0.10 - 0.20 and 0.20 - 0.30 m. The samples were prepared and analyzed in the soil physics laboratory of UFPR. The data obtained were submitted to multivariate statistics. The VESS mean values differed statistically by treatment, the F treatment presented the highest mean (3.33), deferring from all treatments, but the results found pointed out to acceptable structure quality (Qe) (Qe<3) of the soil structure. The RP showed statistical differences of treatment F with the other treatments, having presented minimal differences in the evaluated layers, the highest mean RP was 3 MPa. Mean values of COT obtained (32 to 55 g/kg-1) did not differ statistically between the production systems. The highest root concentration was observed in the 0 - 0.10 m layer, and this concentration decreased in deeper layers. Thus, of the variables (VESS, RP, COT and root parameters) correlated and compared. The RP correlated positively with the VESS, and both were negatively correlated with the COT and the root variables, and with the increase of the VESS and the PR, the reduction of roots and the COT was observed. Among the systems evaluated, F presented higher values of RP and VESS, but, all systems presented acceptable structure quality (Qe <3) for the development of productive components. However, the different production systems provided structural soil quality, indicating that soil management performed on the studied agricultural production systems has been efficient, providing adequate soil conditions to crops