Estimating Soil Penetration Resistance of Paddy Soils in the Plastic State Using Physical Properties

Abstract

Soil penetration resistance (SPR) is an important indicator for soil strength which not only affects the growth of crop roots and crop yield but also is crucial in the design and selection of agricultural machinery. The determination of SPR in the laboratory is complex and time-consuming, while measuring SPR on-site shows high uncertainty at different times and locations due to soil heterogeneity. Therefore, this paper investigated the impact of soil parameters on SPR for paddy soils in the plastic state and then established a simple regression model to predict SPR using easy-to-obtain soil physical properties, including clay content, water content and density. Using the combined approaches of central composition rotatable design (CCRD) with response surface methodology (RSM), SPR of 20 soil samples from five paddy fields were measured in the laboratory. The results from the experiments showed that the contribution rate of each single factor to SPR from high to low was soil density, clay content and water content. Statistical analysis for the established equation suggested that the p-value for goodness of fit was significant (p < 0.001) and the p-value for lack of fit was insignificant (p > 0.05); meanwhile, the coefficient of determination (R2) was 0.95, indicating that the model was effective in predicting the SPR. Subsequently, the performance of the regression model was validated by comparing the estimated SPR with in situ field measurements, which showed high accuracy, with percent errors within 10%. Our study successfully proposed a method to estimate SPR using easy-to-measure soil properties that could be obtained from sensors in the soil or field investigations, including soil clay content, water content and wet bulk density.

Critical Limits for Soybean and Black Bean Root Growth, Based on Macroporosity and Penetrability, for Soils with Distinct Texture and Management Systems

“…Using microporosity as a reference, obtained by applying a tension of 6 kPa, it is noted that the volumetric moisture at the time of assessing the soil mechanical resistance to penetration, in general, presented values lower or close to those obtained at a tension of 6 kPa (Figure 8). Knowledge of moisture and other physical properties when assessing penetration resistance is important, as soil mechanical resistance to penetration is related to soil moisture, bulk density, and texture [67][68][69]. For example, there was an increase in penetration resistance as the soil reduced moisture, and small differences in soil bulk density affected the penetration resistance as a function of moisture in different ways in a Latossolo Vermelho-Amarelo with 0.366 kg kg −1 clay [68].…”

“…However, there is still a need for further studies to validate those values already identified or to present new values. In addition, crops have different responses to soil limitations; soil bulk density is dependent on soil texture [19] and penetration resistance varies according to soil moisture, bulk density, and texture [38,[67][68][69] according to the three-dimensional variability of the soil and the presence of biopores in compacted soil layers [13,[70][71][72] that enable root growth. All these variables make it difficult to define critical or limiting values for plants, but they should be pursued.…”

Dynamics of soil penetration resistance, moisture depletion pattern and crop productivity determined by mechanized cultivation and lifesaving irrigation in zero till blackgram

“…Soil penetration resistance (SPR) is an important parameter of soil strength, which is considered as an indicator for soil compaction that determines the root growth and crop yield [ 22 ]. Mechanized crop cultivation is of great growing concern as wheel traffic due to employment of transplanter and harvester emerges as potential threat to the subsoil structure, which is irreversible and ultimately lead to harmful soil compaction [ 23 ].…”

“…In addition to the above more plant population per unit area had also depleted more of soil moisture which ultimately resulted in poor yield attributes and yield. Reference [ 22 ] also observed that Soil penetration resistance (SPR) in the compacted soils restricts the crop root growth and water uptake and finally led to yield reduction.…”

Effect of Biostimulant, Manure Stabilizer, and Manure on Soil Physical Properties and Vegetation Status

“…The cone index (CI), also often known as penetration resistance, is considered one of the crucial indicators of soil compaction [42]. Cone index values between 2 and 3 MPa, measured at field capacity, are considered upper limits for root growth [43][44][45].…”