Selected Soil Nutrients Research Articles

Prediction of soil nutrients through PLSR and SVMR models by VIs-NIR reflectance spectroscopy

Though soil nutrients play important roles in maintaining soil fertility and crop growth, their estimation requires direct soil sampling followed by laboratory analysis incurring huge cost and time. In this research work, soil nutrients were predicted using VIs-NIR reflectance spectroscopy (range 350–2500 nm) with Partial Least Squares Regression (PLSR) and Support Vector Machine Regression Model (SVMR) model through principal component analysis. Two hundred soil samples were collected from Tarekswar, Hooghly, West Bengal, India to predict eight selected soil nutrients, such as soil organic carbon (OC), pH, available nitrogen (N), available phosphorus (P), available potassium(K), electric conductivity (EC), zinc (Zn) and soil texture (sand, silt, and clay) levels. The OC content was predicted with sound accuracy (R2: 0.82, RPD: 2.28, RMSE: 0.13, RPIQ: 4.15 FD-SG), followed by P (R2: 0.71, RPD: 1.83, RMSE: 4575, RPIQ: 3.44 1st derivative). The soil parameters sensitive to the particular band of visible spectrum were also identified viz. wavelengths of 409, 444, 591 and 592 nm for OC, 430 and 505 nm for P, 464 nm for K; 580 nm for Zn, 492,511,596 and 698 nm for N; 493, 569 and 665 nm for EC; 492,567 and 652 nm for pH; 457 nm for sand and 515 nm for clay.The soil nutrient levels were predicted by PLSR and SVMR models through PCA and Sentinel 2 imagery and soil suitability map were also generated for seven soil parameters such as OC, pH, EC, N, P, K and clay content. Through map query tool in ArcGIS software environment the PLSR and SVMR model successfully identify the suitability class with level of accuracy of 87.2% and 88.9%, respectively, against the direct soil analysis based suitability mapping.The machine learning technique based soil nutrient and soil suitability prediction can be easily adopted in different regions. This will reduce the cost of laboratory soil analysis and optimize the total time requirement.

Spatial Heterogeneity of Selected Soil Nutrients Related to Torreya grandis cv. Merrillii Plantation in Southeastern China

Chinese Torreya grandis (Torreya grandis cv. Merrillii) is a unique economic tree species in China. Intensive management related to application of chemical fertilizer and herbicides caused serious soil quality degradation of Chinese Torreya grandis plantations. Totally, 120 soil samples were collected from the main disbtributed areas of Chinese Torreya grandis in Southeastern China. In this area, soil pH values varied from 3.68 to 6.78, with a median value of 4.91, implying a trend of acidification. The average concentrations of organic matter, available nitrogen, available phosphorus and available potassium were 27.52 g kg−1, 135.77 mg kg−1, 15.12 mg kg−1, and 153.43 mg kg−1, respectively. The results of spatial analysis revealed that target variables had clear spatial patterns. The soil fertility was relevantly high in most of the study area, with soil nutrient imbalances existing. The stand age had a large effect on soil properties, which were also mainly influenced by human activities. Therefore, it is necessary to change the fertilization method for a sustainable management of Torreya grandis plantation.

Testing the accuracy of Soil Testing Kit® Transchem

Soil testing is key to soil fertility management as it serves as a fertilizer application guide to farmers, scientists and consultants. It gives information on soil nutrient status and its supplying capacity. Laboratory (LB) procedures have been the most reliable approach for soil nutrients analyses. However, it is costly and nonpoint. Thus, the use of in–situ testing kit emerges and becomes prominent. Notwithstanding, applicability of soil testing kit must be validated by laboratory test. This work aimed to examine the reliability/suitability of Soil Testing Kit® Transchem (SK) in determining selected soil nutrients in Sahel Savannah, Nigeria. Twentyfive replicate soil samples were collected from 12°47’86’’-12°20’96’’N and 4°38’37’’-4°188’02’’E, Kebbi State Nigeria and used to test soil pH, N, P, K and soil organic carbon (SOC) by SK and LB. The SK uses colour chart and comparator for rating nutrients status qualitatively into; low, medium and high and up to very high for P. The LB results were transformed to qualitative data by corresponding the values with soil rating standardinto low, medium and high. To perform statistics, weighting was done by assigning weight load to each category; low = 1, medium = 2 and high = 3. The two methods were compared using t-test, regression and descriptive analyses. Results showed non-significant difference between the two methods for soil contents of N, P and K. However, SK poorly estimated soil pH and SOC. Correlation and regression coefficients (r = 0.915 and R2 = 0.838, respectively) indicated reliability of the SK. It is concluded that SK can be reliably used for N, P, and K but not soil pH and SOC estimation for soils in Sahel savannah of Nigeria.

Spatial and fractal characterization of selected soil nutrients along a catena

Soil nutrient elements influence crop productivity and environmental sustainability and they vary across several slope positions. The objective of the current study was to evaluate the spatial and fractal variability of selected soil macro- and micronutrient elements across five slope positions: summit, shoulder, back, foot, and toe slopes. Triplicate soil samples (0–18 cm) were collected from each slope position from a pasture field planted to tall fescue (Festuca arundinacea syn. schendonorus arundinaceus). Soil nutrient elements analyzed include phosphorus (P), potassium (K), nitrate N (NO3-N), iron (Fe), and manganese (Mn). Additionally, soil pH, bulk density (BD), and soil organic carbon (SOC) were determined. Results show that SOC was 26% higher, while BD was 10% lower at the toe slope compared with the summit. Similarly, NO3-N was 15, 16, 18, and 1% higher at the toe slope position compared with the summit, shoulder, back and foot slopes probably due to nutrient mobility with water flow. Semivariogram analysis showed that the gaussian isotropic model provided be best fit (R2 > 0.97) for all nutrient elements across all slope positions. The range of spatial variability (A0) of nutrient elements was between 5.8 (K at the backslope position) and 71.0 m (P and Fe at the shoulder and back slope positions, respectively). The fractal dimensions of soil nutrient elements across all slope positions ranged from 0.216 to 1.949 suggesting that as the sampling distance exceeds half the A0, soil nutrient elements tend to become self-similar. The variability in soil nutrient elements from the current study can serve as a useful nutrient application recommendation tool for precision agriculture across five slope positions.

Spatial Modeling of Some Selected Soil Nutrients Using Geostatistical Approach for Jhandutta Block (Bilaspur District), Himachal Pradesh, India

In India, the concept of site-specific nutrient management is very important to increase the productivity particularly under rainfed farming systems. In the Himalayan region, the nutrient management is generally limited to small farms, so there is a need to provide better input to the marginal farmers to avoid the threat from land degradation and emerging nutrient deficiencies. The spatial representation of soil variables is one of the viable options to improve soil fertility by soil-specific nutrient management. Thus, the present study was conducted in the Jhandutta block (Bilaspur district), Himachal Pradesh, India, to assess the spatial variability of some selected soil nutrients. A total of 402 soil samples were collected and analyzed. The log transformation was applied to achieve the normality followed by variogram analysis with a geostatistical approach to develop spatial distribution map using ordinary kriging. Semivariogram was calculated to obtain modeling parameters (nugget, sill and range) that helped to identify the minimum sampling distance for better spatial autocorrelation. In the study area, the exponential model was found to be the best-fitted model. Moreover, the geostatistical approach and the spatial distribution maps in GIS platform inferred the current status of soil nutrients with moderate spatial dependence for most of the soil characteristics. Principal component analysis was carried out to aggregate soil variables in groups and finally five PCs with eigenvalues > 1 accounting for 64.4 per cent of the total variance in the dataset. The spatial distribution of the soil nutrients is strongly influenced by environmental and natural factors. The spatial distribution map delineated those areas which need site-specific nutrient management for sustainable agriculture.

The Influences of Different Methods of Grassland Renovation on the Weight of Post-Harvest Residues and the Abundance of Selected Soil Nutrients

In Poland, half of the grassland is neglected and requires renovation, which was the reason for starting this research project. The aim of this research was to study the grassland habitat of lowland central Poland that has water-deficient, slightly acidic mineral soil, in the years 2013–2016. Specifically, the impact of three methods of grassland renovation on the dry matter yield and the weight of post-harvest residues, as well as on the content of particular nutrient components in the soil, were determined. Three legume–grass mixtures were used for the renovation. The study shows that the method of renovation (ploughing, harrowing, and herbicide + direct sowing) did not have a significant effect on the dry matter yield nor on the weight of the post-harvest residues or the content in the soil of some nutrients. The highest yield was obtained from the “Original” mixture with 50% of legumes in the seed mix. After the renovation, 5.03–7.17 t·ha−1 of post-harvest residues were obtained (mainly grasses and roots of plants, 68.7–71.1%). After three years from renovation, the soil pH significantly decreased and the content of Ca and Mg increased, while the nitrogen, phosphorus, potassium, and Corg compounds remained at an unchanged level. The concentration of various forms of nitrogen, P2O5, K2O, Ca, and Corg decreased in the deeper soil layer (down to 60 cm).

Influence of Cover Crop, Tillage, and Crop Rotation Management on Soil Nutrients

Cover cropping, tillage and crop rotation management can influence soil nutrient availability and crop yield through changes in soil physical, chemical and biological processes. The objective of this study was to evaluate the influence of three years of cover crop, tillage, and crop rotation on selected soil nutrients. Twenty-four plots each of corn (Zea mays) and soybean (Glycine max) were established on a 4.05 ha field and arranged in a three-factor factorial design. The three factors (treatments) were two methods of tillage (no-tillage (NT) vs. moldboard plow [conventional] tillage (CT)), two types of cover crop (no cover crop (NC) vs. cover crop (CC)) and four typess of rotation (continuous corn, continuous soybean, corn/soybean and soybean/corn). Soil samples were taken each year at four different depths in each plot; 0–10 cm, 10–20 cm, 20–40 cm and 40–60 cm, and analyzed for soil nutrients: calcium (Ca), magnesium (Mg), nitrogen (NO3 and NH4), potassium (K), phosphorus (P), sulfur (S), sodium (Na), iron (Fe), manganese (Mn) and copper (Cu). The results in the first year showed that CT increased NO3-N availability by 40% compared with NT. In the second year, NH4-N was 8% lower under CC compared with NC management. In the third year, P was 12% greater under CC management compared with NC management. Thus, CC can enhance crop production systems by increasing P availability and scavenging excess NH4-N from the soil, but longer-term studies are needed to evaluate long-term effects.

Distribution of Selected Soil Nutrients in Aggregate Sizes of Soils Under Different Geologic Formations in Southeast Nigeria

Distribution of Selected Soil Nutrients in Aggregate Sizes of Soils Under Different Geologic Formations in Southeast Nigeria

Poultry Litter Band Placement in No‐Till Cotton Affects Soil Nutrient Accumulation and Conservation

Core Ideas Applying poultry litter in bands below the soil surface leads to greater conservation of most litter‐derived nutrients. Fertilizing cotton with poultry litter, despite supplying additional Mn, leads to reduced extractable soil Mn and tissue Mn levels. A yearly application of 6.1 Mg ha‐1 poultry litter for three consecutive years failed to increase soil total C and N. The effect of subsurface poultry litter band placement relative to the plant row on long‐term nutrient conservation has not been fully investigated. The objective of this study was to determine whether poultry litter band placement affects the accumulation and conservation of selected soil nutrients in a no‐till cotton (Gossypium hirsutum L.) cropping system. The treatments consisted of an average of 6.1 Mg ha‐1 litter applied in 1.02‐m‐spaced subsurface bands (wide, SSw), 0.30‐m‐spaced subsurface bands (narrow, SSn), or 0.30‐m‐spaced surface bands (narrow, SFn); an unfertilized control (UTC); and a soil test‐based synthetic fertilizer treatment (Std). The results showed, relative to the Std, poultry litter, regardless of the placement, resulted in accumulation of extractable soil P, K, Mg, and Zn but not total C or N. A key finding in this study is that litter, despite supplying a 3‐yr total of 10.2 kg ha‐1 Mn, reduced extractable soil Mn by an average of 20% and cotton tissue Mn by as much as 40% relative to the Std treatment. The accumulation of extractable soil P and K and to some extent Mg and Zn was greater when litter was applied by subsurface rather than surface banding. The difference between the SSw and SSn treatments in extractable nutrient conservation was not consistent. Overall, this study showed applying poultry litter in subsurface bands rather than surface bands leads to greater conservation of nutrients. Regardless of the band placement, poultry litter reduced tissue and extractable soil Mn which may be beneficial to cotton production in soils with marginally low pH.

Modelling responses of western Amazonian palms to soil nutrients

SummaryUnderstanding the responses of individual plant species along different edaphic gradients is a key question in ecology, with implications to community assembly, functioning of forest ecosystems, niche theory and conservation planning. In tropical rain forests, responses to soil nutrients have been described only for a handful of species. Even abundant and conspicuous components of the forest, such as the palms (Arecaceae), remain largely unknown in this respect.We inventoried all palm species and analysed soil chemistry in 96 sites across western Amazonia to (i) assess the relative importance of some micronutrients vs. macronutrients as drivers of patterns in palm species composition, (ii) model the response shapes of 61 palm taxa and of canopy vs. understorey palms along gradients of selected soil nutrients, (iii) determine if the response shapes of conspecific palm varieties differ in relation to the most important observed soil nutrient and (iv) assess if the rank order of the most abundant canopy species changes along edaphic gradients.Patterns in palm species composition were best explained by Mehlich‐III extractable exchangeable bases (Ca, K, Mg) and phosphorus (P), with the different palm species clearly separating along the soil cation concentration gradient. All 61 palm taxa exhibited statistical responses along soil nutrient gradients. Response shapes in relation to exchangeable bases varied among bimodal skewed (51% of species), unimodal skewed (47%) and monotonic (2%).There were no significant differences between canopy vs. understorey species in their mean response shapes to the exchangeable bases, but canopy species had significantly higher mean optimum value for soil P and greater mean niche width along the Ca, K, Mg, P and boron (B) gradients. Varieties of the same species ofBactris,DesmoncusandGeonomagenerally had different response shapes and different optima for the exchangeable bases.Synthesis. Among the soil variables we studied, macronutrients (especially exchangeable bases and P) emerged as more important than micronutrients in predicting species abundances in palm communities of western Amazonian non‐inundated forests. Non‐Gaussian responses were predominant, conspecific palm varieties exhibited different response types, and the rank order of dominance of canopy palms varied along the gradients of exchangeable bases and P. Together, these findings advance niche theory about palms and may be used for generating better predictive models of palm species distributions and for experimental studies that search for the physiological mechanisms underlying inter‐ and infra‐specific trade‐offs along edaphic gradients.

Plant interactions with soils conditioned by different vegetation: A potential explanation of Bromus tectorum L. invasion into salt-deserts?

Invasion by Bromus tectorum L. may condition the soil and increase nutrient availability. We hypothesized that nutrient poor soils of the arid Honey Lake Valley of northeastern California U.S.A., similar in physical and chemical properties, but conditioned by either B. tectorum, Krascheninnikovia lanata, or Artemisia tridentata, would differ as a rooting medium. These soil/vegetation types were placed in equal volumes in replicate 5400 cm3 cylindrical containers, the template removed, and sown to B. tectorum or Leymus triticoides; controls were left unplanted. At harvest, root mass, root nutrient concentrations, and selected soil nutrients were quantified for each soil/vegetation type. Root mass was statistically similar among soil/vegetation types and seeded plants. After harvest, and relative to unplanted controls, B. tectorum invaded soil lost a greater proportion of several nutrients than the other soil/vegetation types suggesting greater nutrient uptake from that soil. Soil/vegetation types planted to B. tectorum had significantly greater depletion of soil nutrients compared to soils planted to L. triticoides. Soil invaded by B. tectorum had greater nutrient availability than similar soil conditioned by A. tridentata or K. lanata and offers a plausible explanation of why this exotic annual grass has been able to invade nutrient poor salt-desert ecosystems.

Effects of land use practices on soil organic carbon, nitrogen and phosphorus in river Nzoia drainage basin, Kenya

Land use activities along River Nzoia Drainage Basin, Kenya, include cultivation along the river banks, over grazing, deforestation, draining of wetlands for horticulture, harvesting of sand and brick-making. These activities have brought about changes in soil properties in the drainage basin adversely affecting farming output and the ecosystem in general. Consequently, it is important to understand how the different land use activities influence the soil properties in order to design and implement effective soil management strategies. This study examined the effects of land use practices on selected soil nutrients in Nzoia River Drainage Basin in Bungoma County. Cultivation and grazing were identified as important land use practices, while undisturbed sites were treated as controls. Land use practices along the river were identified by actual surveying of the study area. Secondary data on land use practices were obtained from technical reports, from local authorities and government offices. Soil samples were collected from different land use areas using randomly placed 5mx5m quadrats. Solis were collected at depths of 15cm in zigzag grid layout in each sample quadrat using soil auger. A total of 72 soil samples were collected in the study sites and analyzed for total nitrogen (N), available phosphorus (P) and organic carbon (C). Analysis of variance and correlation were performed to determine the significant land use practices affecting soil N, C and P. Cultivation had a significant effect on soil organic C mean value of 1.91 but negatively correlated with total Nitrogen and soil C while undisturbed sites exhibited positive correlation with C (P≤ 0.05). On the basis of our findings, it is recommended that conservation agriculture be practiced in the River Nzoia and its drainage system.

Poultry Litter Time and Method of Application Effects on Corn Yield

Adopting efficient management practices for using poultry litter (PL) as an alternative to commercial fertilizer is critical for increased N use efficiency. This 3-year study investigated effects of application time (fall and spring) and method of application (soil incorporation and nonincorporation) of three PL rates and NH4NO3 (146 kg N ha−1) on availability of selected soil nutrients and corn (Zea mays L.) grain yield in northern Alabama. The plant-available N rates supplied by the PL were 68 kg N ha−1 (low), 135 kg N ha−1 (medium), and 270 kg N ha−1 (high). Soil inorganic N, Mehlich-3–extractable P, and available K were measured before planting in April, mid-season in June or July, and postharvest in October or November. Averaged across the 3 years, grain yield from the high PL rate was similar to that of the medium PL rate when spring applied. The medium PL rate resulted in 800 kg ha−1 greater grain yield than NH4NO3 from both spring and fall applications. Incorporation of the medium PL rate increased grain yield 590 kg ha−1 and NH4NO3 by 480 kg ha−1, respectively, than nonincorporation but no yield advantage of incorporating the low and high PL rates. Inorganic N, Mehlich-3–extractable P, and available K were highest from mid-season sampling and from spring than fall applications. When N sources were incorporated, the medium PL rate resulted in greater N and P uptake. Results from this study suggest that fall application of NH4NO3 and PL beyond the medium rate should not be encouraged for warm climatic conditions.

Assessment of selected soil nutrients and irrigation water quality in the dryland area of Chivi district, Zimbabwe

The levels of selected nutrients in soils and chemical composition of irrigation water were investigated in 16 villages from the dryland areas of Chivi District in Zimbabwe. The objective was to generate a biophysical knowledge base on the soil fertility status across different villages, and to relate it to site history, management and quality of surface and groundwater used for irrigation. Soil samples were collected from the fields, gardens, cultivated vleis, and virgin land while irrigation water samples were collected from rivers, vlei and shallow wells used to irrigate horticultural crops. Results revealed medium to deficient levels of nitrogen (N) and phosphorus (P) (>75% of the sampled units), and to a lesser degree, potential soil acidity problems on selected fields. The considerably higher soil pH and exchangeable bases in the irrigated gardens and vleis than in the fields and virgin land reflected the impact of management and land utilization. The chemical quality of the sampled water used for irrigation of horticultural crops all showed high chloride hazard. There was need to ascertain the magnitude of crop productivity against applied soil fertility inputs to establish the level and rate of nutrients mining from the soils. Key words: Soil, fertility, dryland, desertification, irrigation.

Environmental Parameters Affecting the Species Diversity Along the Aliakmon River, North Greece

The annual distribution of aquatic and coastal macrophytes in five selected sites along the Aliakmon River was studied from January 2005 to December 2005 in Northern Greece. Soil and water chemical parameters in these sites were also evaluated. A total of 75 taxa were recorded belonging to 37 families and 53 genera. The majority of the macrophytes belonged to coastal plants (76%), whereas the rest of the macrophytes belonged to aquatic plants (24%). Species of the family Asteraceae were dominant among coastal plants, whereas species of the family Potamogetonaceae were dominant among aquatic plants. Soil samples from the site of Dam of Veria had higher pH and electric conductivity (80-100 cm depth), whereas CaCO3 contents were significantly higher in soil samples from the area of P. Prodromos (60-80 cm depth). Most physicochemical water parameters as well as selected soil nutrients and major ionic components showed an increase during the low charge period (fall) compared to with the high charge period (spring), especially in parameters associated with agricultural activity. Furthermore, there was an increase in most examined values moving towards the delta of the river.

Availability of Selected Soil Nutrients in Relation to Land Use and Landscape Position

Availability of Selected Soil Nutrients in Relation to Land Use and Landscape Position

Soil nutrient contents, microbial properties and maize yield under long-term legume-based crop rotation and fertilization: a comparison of residual effect of manure and NPK fertilizers

A study was conducted in a field experiment that has been ongoing for over 60 years at the University of Pretoria, South Africa. The aim was to compare the residual effects of manure and NPK fertilizers on selected soil nutrients, microbial properties, C and N inputs, maize tissue nutrient concentration and yield under long-term crop rotation. Total organic C, total N and available P levels were increased owing to residuai effects of manure alone or in combination with NPK fertilizers. C input in NPK-fertilized plots was about 47% higher than in manured plots. The estimated fixed N ranged from 52 kg ha−1 in the NPK plots to 164 kg ha−1 in the control plots. Increases in nutrient contents of manured plots were not reflected in microbial properties of the soil. Microbial biomass and numbers were generally higher in the NPK-fertilized than in the manured plots. The differential responses were attributed largely to differences in decomposability of organic materials. Organic material in the NPK treatment appeared to have higher turnover rates than in other treatments, suggesting that C limitation in soils of low C but good nutrient supply may be compensated by the high turnover rate of available organic materials.

An investigation of the influence of human disturbance on selected soil nutrients in Narok District, Kenya

Selected soil nutrients were analysed purposely to establish whether they display a spatial pattern due to environmental factors and whether the pattern has been affected by human activities. Data analysis involved descriptive and canonical variate analysis. Except for grassland and shrubland sites, mean carbon, nitrogen, phosphorus, most base cations and copper in the 0–10 cm depth is low for disturbed sites. Within profile data are closer to each other than to data between profiles, suggesting that the former are chemically similar, and that the combined effects of underlying factors is similar. A two-dimensional ordination using canonical discriminant analysis suggests three soil sample clusters that are largely determined by altitude and moisture gradient. Sample ordination of group means show differences between disturbed and undisturbed forest and grassland site categories, suggesting the overriding role of human disturbance over environmental factors on soil nutrients.