Content Of Soil Particles Research Articles

Enhancing soil particle content prediction accuracy: advanced hyperspectral analysis and machine learning models

Enhancing soil particle content prediction accuracy: advanced hyperspectral analysis and machine learning models

Determining the parameters of the milling coulter of the sod seeder

For strip sowing of grass seeds into the sod, a milling coulter with bladed knives has been developed. To determine the optimal parameters and modes of operation of the milling coulter with lamellar knives, a three-level Box-Benkin plan for three factors was implemented. Regression models of the developed milling working body are obtained. An increase in the peripheral speed of the knives of the milling working body significantly improves the quality of tillage, regardless of the number of knives. An increase in the number of knives of the milling coulter also causes an increase in the content of soil particles of 0...25 mm, and the transition from two knives to four ensures its increase by 15.6...20.8%, moreover, the replacement of four knives with six knives - only by 5.8...7.3%. The minimum energy consumption of the milling working body with six bladed knives is 2.0…2.2 kW, which was obtained at a peripheral speed of the knives of 6.0…6.4 m/s. The maximum content of soil fractions 0…10 mm and 0…25 mm, respectively, 69.8% and 91.8%, provides a milling coulter with lamellar knives at their peripheral speed of 8.0…8.4 m/s.

Soil Texture Explains Soil Sensitivity to C and N Losses from Whole-Tree Harvesting in the Boreal Forest

The use of forest biomass to produce energy is increasingly viewed as a means to reduce fossil fuel consumption and mitigate global warming. However, the impact of such practices on soils in the long term is not well known. We revisited forest plots that were subjected to either whole-tree (WTH, n = 86) or stem-only (SOH, n = 110) harvesting 30 years ago in the boreal forest in Quebec, Canada. The objective of the present study was to find soil properties that could explain the lower soil C and N stocks at the sites subjected to WTH compared to SOH after 30 years. Compared to SOH, lower soil C and N stocks attributable to WTH occurred when soil particle content <20 µm was below 30%. The theoretical separation of soil organic matter into two fractions according to soil particle content <20 µm—a recalcitrant and a labile fraction—could explain the observed pattern of soil C and N differences between WTH and SOH. Imperfect or poor soil drainage conditions were also associated with lower soil C and N in WTH compared to SOH. Limiting additional biomass harvesting from these sites would help to preserve soil C and N from potential losses.

Seagrass blue carbon stocks and sequestration rates in the Colombian Caribbean.

Seagrass ecosystems rank amongst the most efficient natural carbon sinks on earth, sequestering CO2 through photosynthesis and storing organic carbon (Corg) underneath their soils for millennia and thereby, mitigating climate change. However, estimates of Corg stocks and accumulation rates in seagrass meadows (blue carbon) are restricted to few regions, and further information on spatial variability is required to derive robust global estimates. Here we studied soil Corg stocks and accumulation rates in seagrass meadows across the Colombian Caribbean. We estimated that Thalassia testudinum meadows store 241 ± 118 Mg Corg ha−1 (mean ± SD) in the top 1 m-thick soils, accumulated at rates of 122 ± 62 and 15 ± 7 g Corg m−2 year−1 over the last ~ 70 years and up to 2000 years, respectively. The tropical climate of the Caribbean Sea and associated sediment run-off, together with the relatively high primary production of T. testudinum, influencing biotic and abiotic drivers of Corg storage linked to seagrass and soil respiration rates, explains their relatively high Corg stocks and accumulation rates when compared to other meadows globally. Differences in soil Corg storage among Colombian Caribbean regions are largely linked to differences in the relative contribution of Corg sources to the soil Corg pool (seagrass, algae Halimeda tuna, mangrove and seston) and the content of soil particles < 0.016 mm binding Corg and enhancing its preservation. Despite the moderate areal extent of T. testudinum in the Colombian Caribbean (661 km2), it sequesters around 0.3 Tg CO2 year−1, which is equivalent to ~ 0.4% of CO2 emissions from fossil fuels in Colombia. This study adds data from a new region to a growing dataset on seagrass blue carbon and further explores differences in meadow Corg storage based on biotic and abiotic environmental factors, while providing the basis for the implementation of seagrass blue carbon strategies in Colombia.

Optimization of the border size on the irrigation district scale – Example of the Hetao irrigation district

To improve the performance of border irrigation, this study analyzed the spatial variability characteristics of the soil particle content and bulk density, based on soil physical parameters measured at 86 sampling points in the Hetao irrigation district (HID). The soil hydraulic parameters were determined using the RETC, and HYDRUS-1D was then adopted to estimate infiltration parameters of the Kostiakov equation at different locations. The optimal layout patterns of border size were proposed under the consideration of various combinations of different typical soil textures and field slopes by WinSRFR. The results indicated that the spatial distributions of clay and silt particle contents were generally high in the middle and low at both sides of the HID, while the sand was the opposite. The results proved that the soil physical parameters are only to be measured at depths of 0–20 and 20–40 cm to meet the needs of infiltration parameter estimation which can significantly reduce the workload of soil sample collection. Moreover, two types of optimal border layouts of different combinations of the soil textures (silt loam and silt clay loam) and field slopes (no more than 1‰, 1–3‰, and 3–5‰) were proposed, which can guarantee the application efficiency and distribution uniformity no less than 85%, and be the guidance for practical field irrigation in the HID.

Convolutional Neural Network approach for the prediction of Soil texture properties

Background/Objectives: The main objective is to achieve improved performance of soil properties prediction for hyperspectral data. In this work, convolutional neural network is trained to understand the pattern of hyperspectral data by spatial interpolation. Methods/Statistical analysis: The proposed methodology is used to predict six soil properties- Organic Carbon content (OC), Cation Exchange Capacity (CEC), Nitrogen Content (N), pH level in water, Clay particle and Sand Particle. Soil texture which defines the relative content of soil particles is determined by the percentage of clay, sand and silt in the soil. The input to the Convolutional Neural Network (CNN) is the Hyperspectral data in the form of multiple arrays. The statistical evaluation of model performance is evaluated using root-mean-square error and r square. Findings: In this research, deep learning approach is used to capture the pattern hidden in the soil. Deep learning is a kind of neural network which can model complex relationship for representing non-linearity for a scalable data. The main challenge is predicting a soil type, as it involves complex structural characteristics and soil features. Novelty/Improvements: The performance of soil texture prediction is improved by automatic feature learning capability in the proposed CNN model. The average rmse value obtained in proposed method for all the six soil texture properties is 5.68%. Keywords: Soil texture; convolutional neural network; hyperspectral data; deep learning

Effect of Soil Particle Sizes on Determination of pH, Oxidizable Organic Carbon and Available Phosphate

Soil analysis is integral part of present agricultural farming, where soil samples are particularly determines with 2 mm sieved soil. It is highly related that finer particles pass through 80 mesh (0.2 mm) size had better interaction with concentrated chemical solution or extractant. Total 136 number of soil sample were collected from different agricultural land of Terai region of West Bengal to conducted the study on effect of soil particle sizes passes through 20 mesh (2 mm) and 80 mesh (0.2 mm) sieve on soil pH, oxidizable organic carbon and available phosphate. Thus, each sample was portioned into two particle size classes. Such as ‘80 mesh soil particles’ and ‘20 mesh soil particles’. The pH, oxidizable organic carbon (OCC) and available phosphate contents of two particle sizes of each soil sample were determined and compared. The maximum difference of 0.2 unit was recorded in case of pH analysis with both sieve sizes. The mean organic carbon content of soil particles that passed through 20 mesh 80 mesh sieve was 0.674 and 0.683 respectively, which further signifies organic carbon content value of 80 mesh soil particle size was slightly greater than that of 20 mesh soil particle size. The value of P content by different sieve size had maximum difference 0.2 kg P2O5 ha-1 and for some soils there was no difference. The difference mean of phosphate values of two particle sizes was 0.134 only. This difference is neglected for crop production. Thus, soil sieved through two sieve sizes 20 mesh 80 mesh sieve had no effect with soil pH, little influence on OCC and negligible effect on available phosphate content.

Changes in mineral-associated carbon and nitrogen by long-term fertilization and sequestration potential with various cropping across China dry croplands

Mineral-associated organic carbon (MOC) and mineral-associated nitrogen (MN) are the major pools of total soil organic carbon (TSOC) and total nitrogen (TN) stocks. Thus, it is important to understand the impact of agricultural practices on MOC and MN stocks and capacities. The present study aimed to explore how the application of various fertilizers and crop rotation affect MOC and MN, and how improved management practices sequester carbon and nitrogen as MOC and MN to mitigate climate change. Twenty-one long-term experiments across China dry croplands with various soil types and crop rotations were involved to investigate the effects of the application of various fertilizers on MOC and MN. Results showed that mineral fertilizers combined with manure significantly increased TSOC (62 %) and TN (57 %), and MOC (33 %) and MN (32 %) concentrations, respectively, resulting in decreased ratios of MOC/TSOC (0.59) and MN/TN (0.47). Moreover, mineral fertilizers with straw significantly increased MOC/TSOC ratio, but had no effects on MN/TN ratio compared with mineral fertilizer application (0.72−0.77). Significantly positive linear correlations were observed between MOC (MN) concentrations and the mass proportion of fine soil particles (<20 μm). Further analysis suggested that TN, TSOC, crop rotation (e.g., wheat-maize, wheat-soybean, maize-soybean, maize-rape, and maize monoculture), and fine soil particle content were the key regulating factors, which accounted for about72 % of the variations of MOC and MN concentration. Boundary line analysis suggested that MOC and MN had the potential to increase by 48 % and 39 %, respectively. In conclusion, main dry croplands in China might sequester an additional 527 Tg for MOC and 37 Tg for MN with appropriate crop rotation and manure application.

Particle-size distribution and heavy metals accumulation in soils of Rostov-on-Don

The surface horizons of the soils of traffic areas of Rostov-on-Don are characterized almost twice higher content of soil particles from 1 mm to 0,01 mm than native chernozems. The higher anthropogenic load provides the higher the content of sand fractions in the particle-size distribution. The accumulation of heavy metals (HM) in urban soils of roadside areas is relatively small, which is also due to a decrease of the soil sorption capacity. Significant excess of the estimated permissible concentrations was detected only for zinc and lead, and the higher the pollution level, the weaker the correlation between the particle size distribution and the HM content. This is justified by the influence of external factors on the accumulation rate of chemical elements.

Identification of sand dune sources in the east Sistan, Iran by using mineralogical and morphoscopic characterization of sediments

Sedimentation in the dune fields of the Sistan Plain of Iran is the result of deposition of fine-grained sediment downstream of the Helmand River. Due to poor adhesion and low moisture content of soil particles, and the strong renowned Levar wind, dune fields mostly of Barchan and Nebkha types are created. This study aims to assess the physical, morphological and mineralogical characteristics of surface (S) and sub-surface (S-S) sediments and their genetic relationships with the aeolian sand surface. For this purpose, 48 S and S-S sand samples were prepared from Niatak Corridor (NC) east of Sistan and were analyzed to determine their physical and mineralogical properties by dry sieving, scanning electron microscopy (SEM) and optical microscopy methods. Results show that the physical characteristics of S and S-S sand particles, such as sorting, roundness, minimum elongation projection, Riley sphericity, morphoscopic and mineralogical characteristics, have no significant difference. The study of thin sections showed that all samples generally contain quartz, feldspar, calcite, gypsum and lithic components. This confirms that the source of S sand dunes is local and consists of the buried layers of sands in the close vicinity. Therefore, the Hamoun Lake are most likely not a source of regional sands. The local existence of Yardang also supports the conclusion of this research.

Soil particle composition, fractal dimension and their effects on soil properties following sand-binding revegetation within straw checkerboard in Tengger Desert, China

This study aims to elucidate the effects of soil particle composition and fractal dimension on soil physical and chemical properties following sand-binding revegetation within straw checkerboard in south-eastern Tengger Desert. Three afforested plantations in the year of 2016 (i.e., 1 year), 2013 (i.e., 4 years) and 1987 (i.e., 30 years) were selected as study sites, with the adjacent mobile sand land as control (CK). We measured soil particle composition, soil fractal dimension, and the changes of soil physical and chemical properties. The relationship between soil particle composition, soil fractal dimension, and soil properties was analyzed. The results showed that contents of soil particle with the size of both 100-250 μm and 250-500 μm were greater than that of 50-100 μm, ranging from 42.5% to 80.1% and from 12.5% to 42.2% relative to that ranging from 0.2% to 20.8%. Contents of soil particle with the size of <2 μm and 2-50 μm were remarka-bly lower than that of 100-250 μm, 250-500 μm and 50-100 μm, ranging from 0 to 1.3% and from 0 to 22.7%, respectively. However, contents of soil particle at the size of 500-1000 μm was the lowest occupying <0.3% of soil particle composition. Soil particle with the size of <2 μm and 2-50 μm were found in the 30-year sites only. Soil particle distribution at the size of 50-100 μm, 100-250 μm, and 250-500 μm followed the order of 30 a>1 a>4 a＞CK, 4 a>1 a>CK>30 a, and CK>1 a>4 a> 30a, respectively. Soil particle with the size of 500-1000 μm occupied little of soil particle composition, with no significant difference between each site. The fractal dimension of soil particles ranged from 0.54 to 2.59. There was significantly greater soil fractal dimension in 30 a in comparison to 4 a, 1 a and CK, with the intermediate values in 4 a and 1 a, and the lowest values in CK. There was a significantly positive correlation of fractal dimension of soil particles with soil particle content of clay, silt, very fine sand, and a significantly negative correlation of fractal dimension of soil particles with soil particle content of medium sand. Fractal dimension of soil particles was positively correlated with soil electrical conductivity, organic carbon, total nitrogen, and carbon-nitrogen ratio, but with no correlation with soil pH and soil water content. Soil particle content at the size of <2 μm, 2-50 μm, and 50-100 μm had a significant positive correlation with soil electrical conductivity, organic carbon, total nitrogen, and carbon-nitrogen ratio, whereas soil particle content at the size of 250-500 μm had a negative correlation with the former four soil indices and soil water content. In addition, there was a significant negative correlation of soil particle content at the size of 500-1000 μm with soil water content. It was concluded that the sand-binding reve-getation within straw checkerboard in Tengger Desert could facilitate the fine soil particles by ameli-orating stressful soil conditions. Long-term succession of revegetation on mobile sand land could enhance soil clay and silt content as well as soil fractal dimension, thus be beneficial for the improvement of soil physical and chemical properties and desertification control.

Life cycle assessment of agromining chain highlights role of erosion control and bioenergy

Agromining is the recovery of valuable heavy metals from soils with high metal concentrations, using hyperaccumulator plants, to produce value added products. It allows the exploitation of low-grade ores for which conventional mining techniques are too expensive and detrimental to the environment. It is also a means for the restoration of closed mines and heavy metal contaminated soils. On lands of low fertility and high concentration in metals, e.g. serpentine soils in the Balkans, it can provide income sources for the local farmers and improve soil fertility and resistance to erosion.We presented here the Life Cycle Assessment of an agromining supply chain. This chain included i) the recovery of nickel from serpentine soils in the Balkans with cropped hyperaccumulator Alyssum murale, and ii) the production of ammonium nickel sulfate hexahydrate (ANSH) from the resulting ashes using hydrometallurgical processes. Results showed that if not controlled by anti-erosion practices, soil loss at farm scale is responsible for significant impacts, especially on human and environmental health, due to the high heavy metal content of soil particles. However, agromining has a similar impact as normal agricultural practices implemented on the territory. It may be used as cover crop instead of leaving bare soils. Its impact would therefore be beneficial. Heat recovery from biomass combustion avoids significant impact, depending on the energy source it may replace. Proper combustion fume filtration and fly ash recovery reduce risks on human health and maximize metal recovery. Byproducts derived from the process may return to the field to compensate nutrient uptake by crops and improve soil fertility. In conclusion, LCA demonstrated that the whole agromining chain offers the opportunity to promote new agricultural practices and preserve valuable resources. Improvements of the industrial processes are however necessary to increase Ni recovery, purity and added value of final products.

Changes of soil particle size fraction along a chronosequence in sandy desertified land: a fundamental process for ecosystem succession and ecological restoration

Soil is composed of particles of different sizes. A fraction of soil particles with different sizes has many vital effects on soil properties such as soil texture, soil porosity, and soil nutrient content. We intended to explore what change took place in soil particle distribution along the chronosequence of restoration and to address what implication this change has for ecosystem restoration. Six restoration ecosystem sites were selected to form a chronosequence in a sandy desertified region, northern China. We examined the relative content of soil particles with different sizes and established an index of enrichment ratio to reflect the change trend of soil particle size fraction. It was showed that soil substrate in this region is mainly composed of coarse sand (>0.25 mm) and fine sand (0.25–0.10 mm), the fraction of which are averagely 23.62 and 57.07 %, respectively. These characteristics make soil coarse, loose and erodible, and to be one of the reasons why sandy desertification was quickly developed in this region. In sandy desertification process, the grades of soil particles were air-classified. Fine sand was strongly enriched 1.36 times than average level, while very fine sand (0.10–0.05 mm) and silt and clay (<0.05 mm) were strongly diluted 0.14 and 0.22 times than average level, respectively. Along with the chronosequence of restoration, very fine sand and silt and clay were deposited and markedly enriched. This change in soil particle size fraction along the chronosequence has many fundamental roles for the subsequent restoration succession of sandy land ecosystem, such as promoting plant growth, strengthening soil anti-erodibility, leading to species replacement and community succession. From this research, it could be concluded that the response of soil particle size fraction to ecological restoration in sandy desertified lands is ecologically valuable, demonstrating that a positive cycle between plant and soil was formed to strengthen the stability of soil-plant system, and the ecosystem has the ability of self-recovering or self-organizing.

Wind erosion on heavy-textured soils: calculation and mapping

The equation that expresses the influence of factors affecting soil aggregates breakdown, and thus wind erosion, originated from the results of laboratory simulations of soil aggregates breakdown due to low temperatures treatment, field measurements of air temperature and soil moisture, and statistical evaluation of gained outcomes. All the analyses, whether field or laboratory, were realized on three different soils from three different localities of the Bílé Karpaty Mountains foothills – Ostrožská Nová Ves, Blatnice pod Svatým Antonínkem, and Suchá Loz. The statistically significant factors, influencing the soil aggregates breakdown, were determined using multiple regression analysis and stepwise regression. Soil moisture content at time of freezing was the most significant factor affecting soil aggregates breakdown, content of soil particles &lt; 0.01 mm was the least significant one. Based on the results of laboratory and field research there was created a map of heavy-textured soils that are vulnerable to wind erosion.

Land Use Patterns Effect on Soil Anti-Erodibility in Low Mountain-Hilly Region

Land use patterns effect on soil anti-erodibility was studied by the combinative means of field investigation and laboratory analysis in low mountain-hilly region. The results showed that he five land use patterns had high proportion of aggregates at the size of &gt;2 mm after dry sieving and had high proportion of aggregates at the size of &lt;0.5 mm after wet sieving. Soil dispersion was mainly reflected in aggregate at the size of 0.05- 0.001 mm under different land use patterns. It was significantly different to land use patterns effect on soil anti-erodibility. Soil anti-erodibility in Chinese fir plantation and Eucalyptus plantation were stronger than those of tea plantation, loquat orchard and abandoned farmland. Water-stable aggregate stability was the highest in Chinese fir plantation, followed by eucalyptus plantations and tea plantations, and water-stable aggregate stability was the lowest in loquat orchards and abandoned farmland. Except for coarse dust, the other soil particle content of the same size had the different change under different land use patterns. The change of status of aggregate and degree of aggregation was opposite to the change of dispersive coefficient under different land use patterns. Water stability index and soil organic matter content in Chinese fir plantation, eucalyptus plantation and loquat orchard was higher than that of abandoned farmland and tea plantation. So, land use patterns of Chinese fir plantation and eucalyptus plantation was reasonable in study area.

Fractal dimension of particle size distribution and its affecting factors in oasis farmland soils in southern marginal zones of Tarim Basin

This paper presents a case study emphasizing the variations in particle size distribution (PSD) characteristics and its influencing factors in Cele Oasis farmland soils in the southern rim of Tarim Basin, Xinjiang, China. The results show significant difference in fractal dimensions (D) of farmland soils in the oasis. D is generally low and varies within 2.11～2.27 range. There exists a significant positive correlation between D and volume content of soil particles 50 μm on the one hand, and between D and soil organic matter content on the other. Whereas the duration of farmland cultivation importantly influences soil PSD, no consistent relation exists between locational distribution of farmland and soil PSD. These results suggest that longterm and appropriate tillage management of farmlands could have such beneficial effects as conserving and improving soil PSD.

Soil fertility in tea plantations in different slope positions and elevation regions

南方低山丘陵区是我国茶园的集中分布区域, 研究其土壤肥力状况是改善茶园土壤养分状况、实现茶叶安全高效生产和可持续发展的基础。选择川西茶区典型低山丘陵茶园, 通过野外调查与样带采样研究土壤养分性质, 利用主成分分析等多元统计方法定量化比较了不同坡位及对照间土壤肥力质量。结果表明：(1)茶园土壤中砂粒含量最高, 平均占总量的39.13%, 其次是黏粒, 粉粒含量居第3位；土壤pH低于4.5, 有机质和全氮含量较低, 速效氮含量较高, 速效磷缺乏, 速效钾变化不显著。与林地、撂荒地相比, 茶园土壤各粒级含量变化规律不明显。有机质和全氮除在下坡位略高于撂荒地外, 其他坡位均小于撂荒地和林地；速效养分变化规律不显著。(2)茶园土壤肥力沿坡面变化明显, 以上坡位为基准, 土壤肥力指数PI值为零, 中坡位<i>PI</i>值(-13.64%)低于上坡位<i>PI</i>值(0)和下坡位<i>PI</i>值(14.39%)。(3)与撂荒地、林地相比, 茶园的土壤肥力综合指数<i>QI</i>值最低。茶园、撂荒地、林地的<i>QI</i>值分别为0.56、1.11和2.73。

Effects of enhanced wind erosion on surface soil texture and characteristics of windblown sediments

It is well documented that wind redistributes and transports soil resources in semiarid ecosystems. However, fewer studies have quantitatively linked wind erosion to detailed grain‐size fractions and associated nutrient content in surface soil and windblown sediment. In this study, we examined (1) the effects of enhanced wind erosion on surface soil particle‐size distribution and (2) carbon (C) and nitrogen (N) characteristics of windblown sediments in a typical desert grassland of southern New Mexico. Our results show that surface soil has become noticeably coarser over a 2‐year period. In particular, content of soil particles in the category of 250–500 μm increased significantly, but soil particles in the fractions of 50–125 μm and &lt;50 μm were significantly depleted. In addition to the enrichment of C and N in the windblown sediments, our results reveal that fine particles (e.g., D &lt; 50 μm) were enriched to a much higher degree at height than C and N. Significantly, our results reveal that nearly 12% of total organic carbon (TOC) and 9% of total nitrogen (TN) were found in the particles with diameter &lt;50 μm, which account for only 1–2% of the mass of windblown sediments. In this wind susceptible environment, our findings suggest that (1) significant soil texture change (e.g., the loss of soil fines) driven by wind erosion could happen rapidly and soil fine particles (e.g., silt and clay) may be depleted within a few years and (2) the loss of even a small fraction of fine particles may indicate a substantial depletion of soil C and N.

Soil losses due to potato harvesting at the regional scale in Belgium

AbstractDuring harvesting of crops, such as sugar beet, potatoes and chicory roots, considerable quantities of soil, consisting of adhering soil, soil clods and stones, are exported from cropland. This soil erosion process is called soil loss due to crop harvesting (SLCH). This study aimed to assess the variability in soil losses caused by potato (Solanum tuberosum L.) harvesting in Belgium and to investigate the role of weather conditions prior to the harvest and regional differences in soil texture on SLCH variability. To meet these objectives, more than 1000 soil tare data measured at a potato‐processing factory during the harvesting seasons of 1999, 2000 and 2001 were analysed. Soil loss was on an average 2.2 t ha−1 per harvest but could be as large as 45 t ha−1 per harvest. The average soil losses per municipality were positively and exponentially related to the average content of soil particles &lt;16 μm. This relationship was in close agreement with a previous field study on SLCH for potatoes in Belgium and could explain why measured soil loss values from a German study were larger than SLCH values for potatoes measured in Belgium. Weather conditions prior to harvest played only a minor role for SLCH variability. As a consequence, SLCH for potatoes harvested mechanically is more variable in space than in time.

Effects of Soil Properties and Depth on Fruit Tree Chlorosis in the Loess Region in Northern China

The loess region in northern China is an important area of apple (Pyrus malus L.) and pear (Pyrus communis L.) production due to its favorable soil and climate. In recent years, as the apple and pear production in this region rapidly increased, more orchards experienced iron deficiency chlorosis. However, information on soil nutrient status and fruit tree chlorosis of this region is scarce. In this research, we collected soil and fruit tree leaf samples from 25 pear and apple orchards (10 chlorotic orchards and 15 nonchlorotic orchards). Soil samples were collected at depths of 0–20 cm, 20–40 cm, 40–60 cm, and 60–80 cm. Soil organic matter, total nitrogen (TN), alkali‐hydrolyzable N, Olsen‐phosphorus (P), ammonium acetate‐potassium (K), DTPA‐iron (Fe), and less than 0.01‐mm soil particle content were analyzed, soil bulk density of 0–10 cm, 10–20 cm, 20–30 cm, and 30–40 cm were also determined. Leaf samples were analyzed for chlorophyll content. Comparison of soil properties was performed between chlorotic orchard soils and nonchlorotic orchard soils; stepwise multiple regression was performed between leaf chlorophyll content and soil properties. The results indicated that those orchard soils were rich in P and K but deficient in Fe. Chlorotic orchard soils contained more K, bicarbonate and less than 0.01‐mm soil particles, and less DTPA‐Fe in certain layers than those of nonchlorotic orchard soils. Leaf chlorophyll content negatively correlated with soil bicarbonate, alkali‐hydrolysable N, and ammonium acetate‐K and positively correlated with TN, DTPA‐Fe, and bulk density at certain depths. Most of these soil properties that have a significant difference between these two kinds of orchard soils or affect leaf chlorophyll content occur below 40 cm in the soil profile. These results suggested that high bicarbonate content and low available Fe content in soils were the primary causes for fruit tree chlorosis in the loess region. Shallow groundwater table in the chlorotic orchards and root growth impairment in the surface soil because of tillage are supposed to be the reason why deeper depth in soil profile play an important role in fruit tree chlorosis in this region.