Critical values of physical attributes of an Ultisol under uses in South of Brazil

Abstract

Changes in the soil structural quality have caused alterations in root growth and agricultural yield. With the purpose of finding critical values of physical parameters and alternative, viable and suitable ways of minimize the soil degradation, this study aimed at quantifying aggregate tensile strength (TS), friability (F), bull density (Bd), total porosity (Tp), macroporosity (Ma), penetration resistance (PR) and total organic carbon (TOC). Relations were established to estimate the structural quality of some parameters of an Ultisol under different uses. The study was carried out on a farm, in the rural area of RS, inserted in the Arroio Moreira waterbasin, Brazil. Disturbed and undisturbed samples were collected from the 0.00 to 0.10 m layer. Regarding TS and soil use, 900 samples were selected, totalling 2700 aggregates. Undisturbed samples (135) were collected for the evaluation of Bd, porosity and PR. The TOC was quantified using 45 aggregates through the dry combustion method. All physical parameters with exception of F are important in monitoring the structural quality.The lowest values of TS, PR and Bd were verified in the soil under fallow, and the highest ones in the soil under pasture. An inverse relation between TS and TOC and between Bd and TOC was verified. Critical values of Bd and TS to crop development might be estimated from the PR.

Soil Mechanical Resistance Penetration after Fifteen Years with Previous Crops and Tillage Systems and Productivity of Green Corn Cob in Northeast Brazil

“…Evidences of this type have been observed in the citrus and eucalyptus farms in the south central region of Sergipe, in areas of Ultisols, causing a decrease, respectively in the useful life of the orchards and lower wood production, due to the presence of cohesive layers. These results are in agreement with [13], that working with the establishment of MRP index to quantify the degree of cohesion, observed that where the values of MRP are higher are also due to lower values of soil moisture. [34], due to this behavior, in the detection of compacted layers, it is necessary to follow the respective values of soil moisture.…”

“…It is observed that the MRP values in this layer exceed 2500 KPa, reaching values higher than 4000 KPa. [13] state that MRP values up to 2500 KPa are considered low and show little limitation on root development. High MRP values increase resistance to root growth [19], reduction in total soil porosity by reducing water storage and restriction of gas flow [20].…”

“…Eight random points were sampled in each of the three replicates, distributed in the plots in a diagonal line, and later a plot was drawn relating the depth in mm and applied force for soil penetration in KPa. The representative graph of MRP was obtained through the PenetroLOG Software [13]. The data concerning the penetrometer were extracted and analyzed to the depth of 400 mm in the soil profile.…”

“…state that the greatest compaction state in no tillage occurs up to 100 mm deep, this being attributed to the confinement of the pressures resulting from the traffic of machines, for the different agricultural operations, besides the In general conditions, in the NT system in relation to CC and MC, they presented two regions with higher MRP values in the superficial layer. [13], t the greatest compaction state in notillage occurs up to 100 mm deep, this being attributed to the confinement of the pressures resulting from the traffic of machines, for the different agricultural operations, besides the natural accommodation of the soil. According to Ralish, [30] in general, these conditions verified in the NT demands less labor and energy, stimulates the flocculation and aggregation processes, reduces the mineralization velocity of the soil organic matter, minimizes erosion , but on the other hand, it favors the appearance of compaction due to not revolving soil and excessive traffic of agricultural machinery and implements.…”

Critical limits of soil physical attributes for corn and black oat in a Xanthic Hapludox

“…Soil compaction especially occurs in notill cultivation because there is intense traffic of agricultural machines (FERREIRA et al, 2020;TRENTIN et al, 2018) or inadequate cropping systems (SOMASUNDARAM et al, 2018) , which affects soil structure and has a direct effect on crop yield (LIMA et al, 2018;MARINS et al, 2018;REICHERT et al, 2009).…”