Soil Penetration Resistance Values Research Articles

The Usefulness of Soil Penetration Resistance Measurements for Improving the Efficiency of Cultivation Technologies

The research results of soil penetration resistance (SPR) tests carried out on sandy clay using four cone probes with different dimensions of the measuring tip are presented in this study. It was indicated that the values of SPR can be used to diagnose the cultivation layer and, on this basis, determine whether it is necessary to cultivate it and select tools for the required treatment. Tests were carried out on three levels of soil density, 1.37, 1.43 and 1.51 g∙cm−3, and two moisture contents, 7.64% and 10.4%. The results show that the probe with the smallest cone with apex angles of 30° and 60° on the least dense soil indicated higher SPR by over 50% more than other probes with the highest cone and the same opening angles. The change in cone opening angle from 30° to 60° led to an increase in probe indications in the range of 10–25%, depending on the diameter of the cone tip. The statistical analysis shows that values of probe indications were statistically significant and were influenced by soil density, probe cone tip dimensions, the surface of the base and the apex angle. The values of SPR are fundamental in diagnosing the quality of the soil’s top layer, determining the necessity of breaking it up, and selecting the optimal tools for this procedure. To improve the efficiency of agricultural crop cultivation technologies. This is particularly important when carrying out cultivation procedures in an environmentally friendly manner. The measurements will help support the introduction of sustainable farming practices, including direct seeding, no-till cultivation, or precision agriculture, reducing soil degradation and increasing environmental benefits.

ASSESSMENT OF SOIL COMPACTION IN AN AREA IN THE URBAN PERIMETER IN THE CITY OF PORTO VELHO/RO

The lack of adequate urban planning, combined with the disorderly growth of Brazilian cities, brings a series of environmental problems resulting from human action. Among these, the pollution of soils and water bodies, soil compaction, and impermeabilization stand out. These issues lead to alterations in surface runoff and natural drainage, resulting in flooding. This study assessed the degree of soil compaction in an area located within the urban perimeter of the municipality of Porto Velho, Rondônia. The assessment was carried out using a Stolf Impact Penetrometer to measure soil penetration resistance at 18 points. Subsequently, interpolation was performed using the Kriging method to generate a continuous surface. The results show that the eastern portion of the study area, where points P6, P12, and P18 are located, and a smaller portion in the southern region, where point P16 is situated, exhibit higher values of soil penetration resistance, ranging from 2.05 to 2.47 MPa. The observed values indicate high compaction of the local clayey soil and are associated with intense demographic occupation in these areas, followed by human activities and the removal of natural vegetation. This, combined with an inefficient urban drainage system, has caused disruptions to the local population.

Spatial variability of edaphic attributes on Coleoptera (Insecta) in land use systems

The alteration of the natural landscape structure affects abiotic conditions and promotes a biological response in the local community. The diversity of edaphic organisms is related to the diversity of other taxa and abiotic characteristics, which represent potential bioindicators of the ecosystem. The objective of this study was to identify which soil attributes explain the beetle community and explore their effects through spatial modeling. The study was conducted in three landscapes in western Santa Catarina (Brazil), located in Chapecó, Pinhalzinho, and São Miguel do Oeste. The land use and cover systems identified were: no-till farming, native forest, pasture, eucalyptus planting, crop-livestock integration, and shrub vegetation. Soil, plant litter, and Coleoptera samples were collected. The variables were selected through the Threshold Indicator Taxa Analysis and spatial modeling by Geostatistics. Higher values of soil penetration resistance, associated with the no-till system, resulted in a lower abundance of Staphylinidae beetles, conditioned by total soil porosity. Lower volumetric moisture values, identified in the no-till system near native vegetation fragments, led to increased abundance of Nitidulidae family beetles, due to the family's adaptability to dry environments. The trend of higher microbial carbon concentration in native vegetation areas explained the greater abundance of Chrysomelidae family beetles in these areas, due to the phytophagous habits of the species in this family. Thus, the Coleoptera community has the potential to serve as bioindicators of soil quality, and their relationships with soil physics, chemical, and microbial attributes can be spatially modeled through Geostatistics.

Comparison of two different artificial neural network models for prediction of soil penetration resistance

A time-varying, nonlinear soil-plant system contains many unknown elements that can be quantified based on analytical methodologies. Artificial Neural Networks (ANNs) are a widely used mathematical computing, modelling, and predicting method that estimates unknown values of variables from known values of others. This paper aims to simulate relationship between soil moisture, bulk density, porosity ratio, depth, and penetration resistance and to estimate soil penetration resistance with the help of ANNs. For this aim, the Generalized Regression Neural network (GRNN) and Radial Basis Function (RBF) models were developed and compared for the estimation of soil penetration resistance values in MATLAB. A dataset of 153 samples was collected from experimental field. From the 153 data, 102 data (33%) were selected for training and the remaining 51 data (67%) were used for testing. The estimation process was implemented 10 replications using randomly selected testing and training data. Mean Squared Error (MSE), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE) were used to evaluate estimation accuracy on the developed ANN methods. Based on MSE, RMSE, MAE and Standard Deviation (SD), statistical results showed that the GRNN modelling presented better results than the RBF model in predicting soil penetration resistance success.

The reconstruction impact on the urban ecosystem park plantings on the example of the Oles Gonchar Dnipro National University Botanical Garden

The article is devoted to the study of the reconstruction impact on park plantings located in the Oles Honchar Dnipro National University Botanical Garden. The reconstruction of the botanical garden was carried out in 2018 and consisted of the removal of 74 old trees, sanitary pruning of some plantings, and the laying of asphalt paths. To determine the impact of the reconstruction on the greenery of the DNU Botanical Garden, four test plots were laid down: plots a and b in the reconstruction area, plots c and d in the unreconstructed area. The following physical parameters of the soil were measured at the test sites: soil penetration resistance, electrical conductivity and moisture. The research was conducted in April – May 2021. Soil penetration resistance is an informative indicator sensitive to anthropogenic impact, its measurement is fast and allows obtaining significant amounts of information in a short time. Electrical conductivity is related to soil moisture and salt content. These indicators, combined with phytoindication methods, allowed us to draw conclusions about the impact of the reconstruction on the soil and green spaces. The landfills differed significantly after reconstruction in terms of the profile distribution of average soil penetration resistance values. The reconstruction area soil is characterized by the appearance of peak soil penetration resistance values at depths of 35–50 cm and 85–90 cm. Polygons a and b have much higher values of topsoil penetration resistance than polygons c and d. The coefficient of variation of soil penetration resistance profile distribution at the test sites in the reconstruction zone also demonstrates a specific character – it has a pronounced peak at a depth of 25–40 cm and gradually decreases with depth. The conclusion about the reconstruction impact on the soil penetration resistance of the botanical garden soil changes was made based on the results of the General Linear Model, which was estimated by the Radj2 index. The distribution of soil electrical conductivity values has a pronounced bell-shaped character. At all the test sites, there is a tendency for electrical conductivity increasing which is positively correlated with moisture. By means of the phytoindicative scales the hemerobia index was determined, which demonstrated a statistically significant linear relationship (p < 0.001) with soil electrical conductivity.

Conservation agriculture practices in a peanut cropping system: Effects on pod yield and soil penetration resistance

ABSTRACT Conservation agriculture principles applied to peanut can reduce soil erosion and production costs when cultivated in rotation with sugarcane. Still, the problem with soil compaction is the leading cause of skepticism about the efficacy of this practice. This research aimed to study the effect of three soil management strategies compared with conventional for peanut cv. IAC-OL3, cultivated in rotation with sugarcane using the MEIOSI (method of intercropping occurring simultaneously) system for agronomic practices with additional analysis on changes in soil physics properties. The trial was conducted in 2019-2020 in Planalto municipality (São Paulo, Brazil) under a green-harvested sugarcane field, using a randomized complete block experimental design. The trial consisted of four soil management treatments (conventional tillage, minimum tillage with chisel, strip-tillage, and no-tillage) with five replications. Although no differences were verified in soil bulk density and porosity among treatments, the highest values of soil penetration resistance were observed in no-tillage treatment for all evaluations (before planting, at the beginning of flowering, and before and after harvesting) in comparison with conventional tillage. The difference in soil penetration resistance among the treatments diminished from planting to the end of the cycle. Furthermore, low soil disturbance and maximum covering with straw significantly increased the available water capacity and reduced the incidence and severity of groundnut ringspot virus (GRSV) on peanut plants. Consequently, both minimum-tillage and no-tillage have increased the pod yield on average by 695 and 991 kg ha -1 more than strip-tillage and conventional tillage, respectively, without differences in terms of quality and pod losses.

Tillage systems impact on soil physical attributes, sugarcane yield and root system propagated by pre-sprouted seedlings

Soil compaction caused by intense machine traffic is a challenge in the sugarcane production system, but its implications can be mitigated by the higher content of soil organic matter and plant root growth provided by conservation management practices (i.e., no-tillage). Thus, we aim to study the impacts of tillage systems on the soil physical attributes, root system and yield of sugarcane propagated by pre-sprouted seedlings. Sugarcane was cultivated under four tillage systems: conventional tillage with harrow (CT); conventional tillage with harrow and subsoiling (CTS), minimum tillage with Rip Strip® equipment (MT) and no-tillage on soybean residue (NT). Soil parameters (soil bulk density, porosity and organic carbon contents) in the 0–60 cm layer, root system (root area and root dry biomass) in the 0–100 cm layer and sugarcane yield were evaluated from 2017 to 2019 during the cane-plant and first-ratoon cane cycles. The no-tillage system showed the highest yields of stalks, biomass and root area of sugarcane even with the highest values of soil penetration resistance and soil bulk density between the rows. The system with Rip Strip® presented the lowest yields of sugarcane stalks. No-tillage had the highest organic carbon content in the topsoil compared to the other tillage systems. The sugarcane yield showed a positive linear relationship with root biomass accumulated in 0–100 cm soil layer. Sugarcane cultivation under no-tillage system provided gains of 15 Mg ha−1 in productivity and higher root dry biomass of the cane-plant cycle in the 0–20 cm soil layer. It also preserves the physical attributes of the soil, increases the soil organic carbon content and favours the increase in the yield and root biomass of sugarcane in both cane-plant and first ratoon cane.

Green Corridors May Sustain Habitats for Earthworms in A Partially Converted Grassland

Permanent grasslands provide a healthy and undisturbed environment. We investigated how mulching altered the soil physicochemical parameters, earthworm abundance, biomass, species composition and vegetation cover compared to grassland and cultivated alfalfa field. Microplots (2 × 2 m) were mulched with either weed control fabric (WF) alone or WF combined with straw (WF + S) on a grassland to grow tomato in Ősagárd (Nógrád county, Hungary) between 2018 and 2021. We had two other microhabitats: a conventionally cultivated alfalfa field (CA) and grassland (GR). We measured soil parameters (physical: soil moisture content (SMC), soil penetration resistance (SPR); chemical: pH, soil organic matter; and biological: earthworm abundance, biomass, species composition and vegetation). SMC was significantly higher on covered plots (WF; WF + S) compared to CA and GR. SPR values were the highest in CA and GR at 20 cm depth. The abundance and biomass of earthworms were the highest in GR and lowest in CA in all seasons. Plant abundance was highly influenced by season and habitat. Despite the higher compaction and lower SMC figures, grass vegetation still provided a more suitable environment for earthworms than mulched plots (WF, WF + S). Therefore, where there is agricultural production on grassland, we suggest leaving uncultivated and uncovered patches as biodiversity corridors.

Is localized soil tillage in the planting row a sustainable alternative for sugarcane cultivation?

The aim of this study was to evaluate the physical quality of the soils by evaluating the variation of soil penetration resistance, resulting from tillage with chiseling in the planting row and in total area, and the possible interferences of the managements in sugarcane yield. The study was carried out in southeastern Brazil, in areas under Oxisol and Ultisol, which are the two soils with the greatest representativeness of sugarcane cultivation in the country. The treatments consisted of soil tillage in total area and localized tillage in the sugarcane planting row, with 10 replicates. Undisturbed soil samples were collected in the 0-0.10, 0.10-0.20, and 0.20-0.40-m soil layers in sugarcane rows and interrows in both soil types for penetration resistance determination in laboratory. Samplings were carried out at three times, the first after soil tillage, the second after sugarcane planting, and the third six months after planting. Compared to the system with tillage in total area, localized tillage promoted higher values of soil penetration resistance in sugarcane interrows. However, this was not enough to reduce the crop yield. In the planting row, there are no differences between tillage types for soil penetration resistance. Localized soil tillage in sugarcane crop is a conservation and sustainable alternative that can replace soil tillage in total area, not interfering in the PR determined in the crop row and not altering the stem yield, regardless of the soil type.

Shear modulus from SPT N-values with different energy values

It is essential to determine low strain shear modulus (Gmax) to model dynamic soil response and estimate the site effects due to earthquakes. Several correlations have been developed between dynamic soil properties and soil penetration resistance values such as N-values from Standard Penetration Test (SPT). However, only a few of the established correlations are often used because of uncertainty over applied hammer energy (EH) and applicability in different regions. Hence, this study aims to signify the importance of EH in N-value corrections, its influence on Gmax estimation, to suggest modification factor for an existing correlation and validate with Downhole and Crosshole measurements. Different SPT corrections are studied besides the energy measurements in the analysis of the correlation between the N-value and Gmax. A previously proposed correlation between measured N-value and Gmax is improved to account for in-situ EH measurement, and the correction factors to account for different hammer energy ratios (ER) are suggested. Modified correlations compared well and agreed within the 95 % confidence bound with the freshly acquired seismic borehole tests data.

Spatial investigation of soil penetration resistance and its impacts on cultivation of ‘BRS Princesa’ banana

The present study aimed to investigate the spatial variability of soil penetration resistance (SPR) in cultivation areas of ‘BRS Princesa’ banana, to evaluate its effects on the chemical and physical attributes of the soil and to indicate localized management. The experiment was carried out in an area of cultivation ‘BRS Princesa’ banana, in which 60 georeferenced points were recorded. SPR was measured from the cone index to 0.40 m depth using an impact penetrometer. Disturbed samples were collected at depths of 0-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 m and the soil attributes pH, Ca, Mg, Al, Na, K, P, H + Al, SB, T Value, V%, total sand, total clay, silt, TOC, POC, MAOC and gravimetric moisture were determined. The data were subjected to descriptive statistics, Pearson’s linear correlation and geostatistical analysis. SPR values in subsurface suggest greater compaction in subsurface and the significant correlations with soil attributes indicate losses for banana plants, so localized management should be carried out. It was found that 46.7% of the total area of the banana plantation does not need to be decompacted, and localized subsoiling at a varying depth is indicated in the other regions.

Soil and water losses along the cultivation cycle of onion in Irati, Brazil

Onion is one of the most important vegetables grown in southern Brazil. However, despite its profitability, little is known about its response to soil erosion throughout its productive cycle divided into 5 stages: S1 (germination), S2 (formation of leaves and roots), S3 (bulbification), S4 (snap) and S5 (harvesting). With the aim of providing knowledge in this matter we have analyzed the intra-cycle dynamics of some parameters such as bulk density (BD), porosity, soil penetration resistance (SPR), and soil and water losses. To do that we have assessed these parameters in 40 random points and at different depths in a representative farm of 3 ha located in the municipality of Irati (Paraná, Brazil). BD was quantified by using the core method, porosity after particle density quantification by the volumetric balloon method, and SPR by impact penetrometer. Soil and water losses were estimated after carrying out 30 rainfall simulations (6 per crop stage). The results showed that bulk density increased progressively and continuously from 1.06 to 1.36 g cm−3. This greater compaction was also observed in the values of SPR that increased from 2.0 to above 3.0 MPa at the end of the cycle. Regarding soil erosion the highest rates were recorded at S4 when onions are snapped (431.0 g m−2). We conclude the occurrence of runoff and soil erosion is a consequence of the increase in soil compaction throughout the cycle provoked by the repeated pass of heavy machinery and workers to apply herbicides and fertilizers. Since soil erosion rates found are relatively high (1437.1 g m−2 y−1) we suggest the progressive implementation of conservationist practices to guarantee its sustainability.

Untrafficked furrowed seedbed sustains soil physical quality in sugarcane mechanized fields

AbstractManagement strategies that reduce machinery traffic, such as creating seedbeds, could be adopted to preserve soil health and reduce soil physical restriction to sugarcane (Saccharum sp.) growth. Field experiments on clayey and sandy loam soils were conducted along four crop seasons (2013–2017) to investigate the changes in bulk density, soil penetration resistance, macroporosity and microporosity in the row and inter‐row positions, as well as sugarcane biomass production (root and stalk yield) under different machinery traffic treatments. The experimental areas were conducted in randomized block design with two treatments and four repetitions. The evaluated treatments were: (a) regular traffic, in which all operations were performed mechanically using regular machinery traffic; and (b) without traffic, in which all field operations (except those used for sunn hemp management and for opening the sugarcane planting furrow) were performed manually without machinery traffic. No critical values of physical properties were identified in either soil type in plots without machinery traffic, indicating the lowest density and soil penetration resistance values, as well as higher macroporosity, where sugarcane seedbed zones had been established. Our findings show that seedbeds resulted in greater root growth and development in the soil profile, mainly in inter‐row positions. Overall, sugarcane stalk yield was similar between the treatments in both soil types. This study reinforces the importance of the planting furrow in keeping suitable soil conditions for plant growth and concludes that sugarcane production in untrafficked seedbeds is an effective strategy to sustain soil physical conditions over the crop cycle, without the need for tillage operations during the (re)planting period.Highlights The use of seedbeds sustains soil physical quality along the crop cycle Most of root biomass were concentrated in the crop‐row Crop‐row position provides adequate soil physical conditions for root growth and plant development Untrafficked furrowed seedbed sustains soil physical quality and makes no‐tillage viable

Effect of Previous Crop Roots on Soil Compaction in 2 Yr Rotations under a No-Tillage System

Compacted soils affect global crop productivity and environmental quality. A field study was conducted from 2014 to 2020 in the northern Great Plains, USA, to evaluate the effect of various rooting systems on soil compaction in 2 yr rotations of camelina (Camelina sativa L.), carinata (Brassica carinata A.) and a cover crop mix planted in place of fallow with durum (Triticum durum D.). The study was designed as a randomized complete block with three replications in a no-tillage system. The soil was classified as Dooley sandy loam (fine-loamy, mixed, superactive, frigid Typic Argiustolls) derived from glacial till parent material. Three measurements of soil penetration resistance (PR) were taken with a penetrometer to a depth of 0–30 cm within each plot. Soil moisture contents were determined using a TDR sensor at the time of PR measurements. Both measurements were monitored prior to planting in spring and after harvest. Initial PR results from spring 2014 showed that all plots had an average of 2.244 MPa between the 8–20 cm depth, due to a history of tillage and wheel traffic caused by various field activities. Covariance analysis indicated that soil PR was not significantly affected by crop type and moisture content. After one cycle of the 2 yr rotation, the 2016 measurements indicated that the compacted layer existed at the same initial depths. However, after two and three cycles, soil PR values were reduced to 1.480, 1.812, 1.775, 1.645 MPa in spring 2018 and 1.568, 1.581, 1.476, 1.458 MPa in 2020 under camelina, carinata, cover crop mix, and durum treatments, respectively. These findings indicate that previous cover crop roots could effectively improve soil compaction by penetrating the compacted layer, decompose over time and form voids and root channels. Although these results are novel and significant, further research is needed on different soils and under cover crops with different root systems to support our findings prior to making any conclusion.

Soil morphostructural characterization and coffee root distribution under agroforestry system with Hevea Brasiliensis

Land use and tillage practices may change soil structure and undermine sustainable agriculture; however, such changes are hardly identified in the short term. In this sense, agroforestry systems have been used to reduce soil degradation and promote sustainable production in coffee plantations. These areas are expected to have well-structured soils and hence improved root distribution. This study aimed to evaluate soil quality by the morphostructural and root distribution analyses comparing open-grown coffee and coffee in agroforestry systems with rubber trees for 19 years, in an Oxisol in northern Paraná State (Brazil). Treatments consisted of open-grown coffee (OG), coffee partially shaded by rubber trees (PSH), and coffee fully shaded by rubber trees (FSH). The mapping of morphostructural features and soil resistance to penetration in “cultural profile” walls identified changes in soil structure resulting from different tillage systems. Root distribution was better in coffee plants grown in PSH and FSH systems. At greater depths, cultural profiles of FSH and PSH showed a larger numbers of roots compared to OG. Among the three systems, PSH provided a better environment for root growth and distribution. This result could be attributed to the high biological activity and interaction between roots and aggregates in that profile. The FSH agroforestry system provided less compact morphological structures and more roots throughout the soil profile. The agroforestry systems presented fewer soil structural changes by tillage operations and lower values of soil penetration resistance. Coffee root distribution was an effective indicator of soil quality and consistent with the morphostructural characterization of cultural profile.

RESISTANCE OF A RED LATOSOL TO PENETRATION: COMPARISON OF PENETROMETERS, MODEL ADJUSTMENT, AND SOIL WATER CONTENT CORRECTION

ABSTRACT Penetration resistance can be determined directly in the field or in the laboratory. However, data obtained using the two methods are not directly comparable. Considering soil moisture influences penetration resistance, penetration resistance data obtained using the two methods can be corrected based on common moisture values. To enable comparison of the data, the measured data should be adjusted using mathematical models. Consequently, the objective of the present study was to compare soil penetration resistance values measured in a Red Latosol using a static penetrometer and a bench-top electronic penetrometer. The comparison was carried out using samples collected from different soil layers, based on moisture levels ranging from 0.15 to 0.28 kg kg-1. In addition, the reliability of some mathematical models was compared using bench-penetrometer data. Finally, the Busscher method and a new proposed method for moisture correction were tested. According to the comparison of results between the equipment, it is necessary to correct data using a linear type equation. The Jakobsen & Dexter (1987) model had the optimal performance (R2: 0.89; RMSD: 0.70). The new proposed corrected method was tested using several reference moisture values and it presented minor (< 0.30 RMSD) and stable errors.

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The article shows the possibility of assessing the level of recreational transformation of public green spaces in terms of the soil penetration resistance and proved that the profile distribution of soil penetration resistance values is an information valuable indicator for establishing the level of recreational load. The measurement of soil penetration resistance within the park Novooleksandrivsky (Melitopol, Ukraine) was performed at 179 points on a quasi-regular grid with a distance between the points of accounting 30–40 m. The soil penetration resistance was revealed to be naturally increases with the growth of the depth of the soil layer from 2.42±0.023 MPa in the soil layer 0‒5 cm to 9.86±0.078 MPa in the soil layer 95‒100 cm. The process of increasing soil penetration resistance with depth is not monotonous, resulting in the presence of local penetration resistance at a depth of 50‒55 or 55‒60 cm. The variability of soil penetration resistance within one layer, which is described by the variation coefficient, is in the range of 6.98‒20.54%. This indicator naturally changes by profile. The high level of variation is peculiar to the top layer of soil 0‒5 cm, where the coefficient of variation of soil penetration resistance is 12.94 %. It is proved that under the influence of recreation there is a formation of functional layering of soil, expressed in the existence of structures in which layers of soil with greater soil penetration resistance are degraded by layers of less penetration resistance. The presence of such features can cause a complex of negative phenomena, which are associated with restriction of moisture penetration into the soil, reducing the migration capacity of air in the soil, limiting the growth of root systems of plants and the movement of animals. Functional layering can form local waterproof horizons that will limit the soil’s ability to absorb moisture. Correlational analysis of the connection of soil penetration resistance and the indicator of recreational load allowed to establish that with the increase of recreational pressure soil penetration resistance increases. The established correlational dependence of soil penetration resistance indicators and the assessment of the level of recreational load allows us to consider the possibility on the basis of penetration resistance data to quantify the level of recreational load. We completed this task with the help of multiple linear regression with the procedure of step-by-step inclusion of predictors in the model. The regression model is statistically significant and has made it easy to explain 46% of the varying indicators of recreational load. The step-by-step inclusion procedure provided an opportunity to choose the 10 most informative predictors for use in the model. The following levels of recreational load were established: low level, below moderate, moderate level, above moderate to high levels, as well as the procedure for indication of these levels based on soil penetration resistance data at different depths. The levels of recreational load were indicated on the basis of the procedure of classification trees on the soil penetration resistance data

MACHINE TRAFFIC AND SOIL PENETRATION RESISTANCE IN GUAVA TREE ORCHARDS

ABSTRACT The study was conducted in irrigated commercial orchards of ‘Paluma’ and ‘Pedro Sato’ guavas, which were mapped with a Garmin GPS unit (Cx60). Sixty five sampling points were marked on a 21 x 21 m sampling grid. Gravimetric humidity and soil penetration resistance (SPR) were evaluated with the help of an automated penetrometer rod with a type 3 cone at a 45º angle (maximum SPR 15,100 kPa). Data with non-normal distribution were analyzed by geostatistics and interpolation by ordinary kriging. SPR values were higher where machine traffic occurs than on the lines where the crop is planted. There was spatial variability of the SPR among the layers evaluated, with the layer between 0.10-0.20 m, on the line of the machine traffic, presenting a higher SPR (&gt;4000 kPa).

SPATIAL VARIABILITY OF SOIL PENETRATION RESISTANCE IN COFFEE GROWING

The intensive use of machines in agriculture tends to cause soil compaction, which can hamper the expansion of root system and the absorption of water and nutrients, thus affecting the crop development. In view of the above, the present study aimed to identify critical zones of soil compaction, through the spatial distribution of soil penetration resistance (SPR), having positions within the coffee rows and soil depth ranges as variables. The study was performed in a coffee plantation of 7.32 ha, belonging to the Bom Jardim Farm, located in the municipality of Bom Sucesso, MG, Brazil. The SPR was measured using a penetrometer in the depth range from 0 to 0.40 m, with discretization in four layers of 0.10 m. The data were interpreted based on geostatistics, in order to identify if there is spatial dependence of the SPR and generate thematic maps demonstrating the variable’s spatial behavior. It is concluded that there is spatial dependence of soil penetration resistance, being possible to use geostatistical tools to generate thematic maps based on classes of soil penetration resistance. The values of SPR in the tractor trail, for layers from 0.10 to 0.20 and from 0.20 to 0.30 m, were classified in the high SPR class and could cause damage to the crop.

Bio-intensive Modulation of Sugarcane Ratoon Rhizosphere for Enhanced Soil Health and Sugarcane Productivity Under Tropical Indian Condition

Intensive cropping and exhaustive nature sugarcane crop in tropical India have led to depletion of inherent soil fertility resulting in serious threat to sustainable sugarcane production. Improving soil organic matter and soil fertility are important factors for sustainable sugarcane production. Microbial consortia comprising of Trichoderma viride, Humicola spp, Paecilomyces lilacinus, Gluconacetobater diazotropicus, Azospiriillum brasilense, and Bacillus subtilis have great potential to recycle crop residue and restore soil fertility which eventually promote sugarcane growth. Field experiments with in situ trash management in plant crop and bio-intensive modulation of sugarcane ratoon rhizosphere in ratoon crops were conducted during 2014, 2015 and 2016 at ICAR—Sugarcane Breeding Institute, Coimbatore, Tamil Nadu, India. The results revealed that green manuring with sunnhemp, in situ trash management and application of 280:62.5:120 kg NPK ha−1 in plant crop sustained the soil health by way of reducing soil bulk density (1.26 kg dm−3), lower soil penetration resistance in the ratoon rhizosphere (1.79, 1.82 and 1.75 MPa) and higher soil organic carbon (0.52%) which in turn increased ratoon cane yield 12.24% (99.02 t ha−1) and sugar yield by 8.64% (12.83 t ha−1) over the control. Further, bio-intensive modulation of ratoon rhizosphere by off barring, trash shredding plus soil incorporation with microbial consortia and application of 350:62.5:120 kg NPK ha−1 in ratoon crop recorded significantly higher cane yield (100.95 t ha−1) and sugar yield (13.19 t ha−1) over the control. The improvement in cane yield and sugar yield to the tune of 16.35 and 14.10% due to bio-intensive modulation of ratoon rhizosphere over control have clearly established that productivity of sugarcane ratoon can be significantly improved with balanced use of fertilizers, green manuring, crop residue recycling and microbial consortia application. Similarly, bio-intensive modulation of sugarcane ratoon rhizosphere (S3) with lowest soil bulk density (1.26 kg dm−3) and soil penetration resistance values (1.69, 1.81, and 1.75 MPa) was found effective in minimising the soil compaction and improving nutrient availability (NPK) with build-up of soil microbial population than control (Trash removal). Based on the results of 3-year field experiments, it is concluded that sunnhemp green manuring and in situ sugarcane trash management coupled with application of 280:62.5:120 kg NPK ha−1 in plant crop followed by bio-intensive modulation of ratoon rhizosphere including off barring, trash shredding and soil incorporation with microbial consortia and application of 350:62.5:120 kg NPK ha−1 in ratoon crop can be recommended for sustaining soil health and sugarcane productivity under wide-row sugarcane planting systems of tropical Indian condition.