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1.
Termites are reported to improve soil physicochemical properties thereby enhance soil fertility of their mound and foraging areas. Empirical study pertaining to these effects is missing in Southwest Ethiopia. For this study, soil samples affected by termite activities were collected at 1 m interval within 0–3 m distance from the base of six termite mounds on gently sloping and sloping land and analyzed for physicochemical parameters. The result of the analysis depicted that soil bulk density (1.38–1.15 g cm?3) and moisture content (21.1–9.9%) decreased with increased distance from the mound base. While clay content decreased with increased distance from the mound base from72.0% to 45.5%, sand and silt contents increased from 8.0% to 21.3% and 19.3% to 28.5%, respectively. PH (6.23), organic carbon (3.85%), total nitrogen (0.4%), cation exchange capacity CEC (30.43 cmol kg?1), exchangeable Ca (13.73 cmol kg?1), Mg (3.15 cmol kg?1), and PBS (56.8%) were higher on termite mounds. While, electrical conductivity (0.03 dS m?1–0.06 dS m?1), exchangeable K (0.52–0.93 cmol kg?1) and Na (0.02–0.03 cmol kg?1) showed increasing trend with the distance from the mound base. Our results indicated that termite mounds are important sinks of organic matter and mineral nutrients, and hence contribute to the enhancement of soil fertility. Thus, for subsistent farmers the uses of termite mounds as a fertilizer present an opportunity to improve agricultural production.  相似文献   

2.
Abstract

Water extraction of trace elements can simulate the concentration of elements in the soil solution from where the plant takes up the elements. The objective of this investigation was to determine the water extractable concentration of seven trace elements (Fe, Mn, Ni, Co, Mo, Pb and Cd) and to assess their relationship with soil properties of the Danube basin in Croatia. Soil samples from the surface layer (0–25 cm) of 74 sites, having different land uses (forest and agricultural land), were collected. Samples were analysed for total and water extractable trace elements as well as for pH, DOC, SOC and CEC. The concentrations of water extractable fraction of trace elements were on average: 20.14 mg kg?1 for Fe, 3.61 mg kg?1 for Mn, 0.07 mg kg?1 for Ni, 0.016 mg kg?1 for Co, 0.01 mg kg?1 for Mo, 0.01 mg kg?1 for Pb and 0.0009 mg kg?1 for Cd. Soil properties were in the following range: pH 4.3–8 (Avg: 6.35), DOC 6.1–73 mg l?1 (Avg: 26 mg l?1), CEC 1.3–24 cmol kg?1 (Avg: 9 cmol kg?1) and SOC 0.5–5% (Avg: 1.7%). The concentration of water extractable fraction of trace elements was significantly correlated with pH (p <0.001), DOC (p <0.001 – p <0.05) and CEC (p <0.001) but their relationship with total content of trace element and SOC was rather weak, suggesting that total metal alone cannot be an indicator of toxicity or deficiency. Results show that pH, DOC and CEC are important soil quality parameters taking part in the solubility control of trace metals in the soil rather than their total concentration. The difference between land uses has been observed as well, suggesting that a change in land use can cause a change in trace element solubility.  相似文献   

3.
The Burdur Lake is located in the southwest of Turkey, and its area has decreased by 40% from 211 km2 in 1975 to 126 km2 in 2019. In this study, we investigated how the soil has changed in the lacustrine material. Three soil profiles were sampled from the former lakebed (chronosequence profiles: P1, 2007; P2, 1994; and P3, 1975), and three soil profiles under different land use types (biosequence profiles: P4, native forest vegetation; P5, agriculture; and P6, lakebed) were sampled. The chronosequence and biosequence soil profiles represented various distances from the Burdur Lake and showed different stages of lacustrine evolution. Soil electrical conductivity (EC; 18.1 to 0.4 dS m-1), exchangeable Na+ (34.7 to 1.4 cmol kg-1) and K+ (0.61 to 0.56 cmol kg-1), and water-soluble Cl- (70.3 to 2.1 cmol L-1) and SO42- (275.9 to 25.0 cmol L-1) decreased with increasing distance from the Burdur Lake, whereas the A horizon thickness (10 to 48 cm), structure formation (0 to 48 cm), gleization-oxidation depth (0 to 79 cm), and montmorillonite and organic matter (OM; 25.9 to 46.0 g kg-1) contents increased in the chronosequence soil profiles. The formation of P3 in the chronosequence and P5 in the biosequence soil profiles increased due to longer exposure to pedogenic processes (time, land use, vegetation, etc.). Changes in EC, exchangeable cation (Na+ and K+) and water-soluble anion (Cl- and SO42-) concentrations of the salt-enriched horizon, OM, gleization-oxidation depth, A horizon thickness, and structure formation of the chronosequence and biosequence soil profiles (especially the topsoil horizon) were highly related to the distance from the Burdur Lake, time, and land use.  相似文献   

4.
The study was conducted to determine the long-term impact of different land uses on carbon sequestration, soil fertility, and microbial indices and to establish their interrelationship in a light-textured hyperthermic Udic Ustochrept. Soil samples were collected from existing land-use systems of (1) Eucalyptus tereticornis, (2) Terminalia chebula, (3) Acacia nilotica, (4) Leucaena leucocephala, (5) Embilica officinalis, (6) Zizyphus spp., and (7) maize–wheat rotation from depths of 0–15, 15–30, and 30–45 cm and examined for pH; organic carbon (OC); electrical conductivity (EC); available nitrogen (N), phosphorus (P), and potassium (K); micronutrients; microbial biomass carbon (MBC); microbial biomass nitrogen (MBN); and microbial biomass phosphorus (MBP). High-density plantations of Eucalyptus teriticornis had a greater potential in sequestering aboveground carbon (472.37 Mg ha?1), compared to widely spaced trees of Acacia nilotica (376.05 Mg ha?1). Eucalyptus teriticornis exhibited the greatest impact in increasing soil OC in all depths, followed by Acaccia nilotica and Terminalia chebula, and the lowest was in agriculture (0.778, 0.749, 0.590, and 0.471%, respectively, in surface soil). Available zinc and iron contents were greatest under Eucalyptus tereticornis, followed by Acacia nilotica, Zizyphus mauritiana, Embilica officinalis, Terminalia chebula, and Leucaena leucocephala. The MBC and MBN were greatest in Eucalyptus tereticornis, followed by Acacia nilotica, and lowest in agriculture. Correlation matrix revealed significant and positive relationships between carbon sequestered with OC, MBC, MBN, and MBP.  相似文献   

5.
Long-term effects of the different combinations of nutrient-management treatments were studied on crop yields of sorghum + cowpea in rotation with cotton + black gram. The effects of rainfall, soil temperature, and evaporation on the status of soil fertility and productivity of crops were also modeled and evaluated using a multivariate regression technique. The study was conducted on a permanent experimental site of rain-fed semi-arid Vertisol at the All-India Coordinated Research Project on Dryland Agriculture, Kovilpatti Centre, India, during 1995 to 2007 using 13 combinations of nutrient-management treatments. Application of 20 kg nitrogen (N) (urea) + 20 kg N [farmyard manure (FYM)] + 20 kg phosphorus (P) ha?1 gave the greatest mean grain yield (2146 kg ha?1) of sorghum and the fourth greatest mean yield (76 kg ha?1) of cowpea under sorghum + cowpea system. The same treatment maintained the greatest mean yield of cotton (546 kg ha?1) and black gram (236 kg ha?1) under a cotton + cowpea system. When soil fertility was monitored, this treatment maintained the greatest mean soil organic carbon (4.4 g kg?1), available soil P (10.9 kg ha?1), and available soil potassium (K) (411 kg ha?1), and the second greatest level of mean available soil N (135 kg ha?1) after the 13-year study. The treatments differed significantly from each other in influencing soil organic carbon (C); available soil N, P, and K; and yield of crops attained under sorghum + cowpea and cotton + black gram rotations. Soil temperature at different soil depths at 07:20 h and rainfall had a significant influence on the status of soil organic C. Based on the prediction models developed between long-term yield and soil fertility variables, 20 kg N (urea) + 20 kg N (FYM) + 20 kg P ha?1 could be prescribed for sorghum + cowpea, and 20 kg N (urea) + 20 kg N (FYM) could be prescribed for cotton + black gram. These combinations of treatments would provide a sustainable yield in the range of 1681 to 2146 kg ha?1 of sorghum, 74 to 76 kg ha?1 of cowpea, 486 to 546 kg ha?1 of cotton, and 180 to 236 kg ha?1 of black gram over the years. Beside assuring greater yields, these soil and nutrient management options would also help in maintaining maximum soil organic C of 3.8 to 4.4 g kg?1 soil, available N of 126 to 135 kg ha?1, available soil P of 8.9 to 10.9 kg ha?1, and available soil K of 392 to 411 kg ha?1 over the years. These prediction models for crop yields and fertility status can help us to understand the quantitative relationships between crop yields and nutrients status in soil. Because black gram is unsustainable, as an alternative, sorghum + cowpea could be rotated with cotton for attaining maximum productivity, assuring sustainability, and maintaining soil fertility on rain-fed semi-arid Vertisol soils.  相似文献   

6.
Abstract

The goal of this study to was compare soils of natural forests converted to teak (Tectona grandis Linn. F) plantations (21.3±5.1 years) in the Offinso and Juaso Forest Districts in the Ashanti region, Ghana. Sites selected for this study were in the moist semi‐deciduous forest zone and had nearly identical physiographic characteristics. In each of three natural forest stands and three teak plantations, 16 soil pits were examined and soil samples from the 0–20 (major rooting zone) and 20–40 cm depths were analyzed for selected chemical and physical properties. In the 0–20 cm depths bulk density significantly increased (1.17 to 1.30 g cm‐3), but soil organic matter (OM) content (13 to 11%), total nitrogen (0.3 to 0.2 %), available phosphorus (4.2 to 1.2 mg kg‐1), and exchangeable potassium (0.4 to 0.3 cmol(+)kg‐1), calcium (17.0 to 12.4 cmol(+)kg‐1), and magnesium (3.8 to 3.2 cmol(+)kg‐1) significantly decreased in soils where natural forests were replaced with teak plantations. Similar results also were found for the 20–40 cm soil depths. The higher nutrient contents in soils under the natural forest may have been due to more litter contributions from understorey vegetation observed there. In the teak plantations nutrient leaching losses may have accelerated due to increased mineralization and the inability of teak to use the increase in available nutrient.  相似文献   

7.
This study analyzes effects of soil and water conservation (SWC) on soil quality and implications to climate change adaptation and mitigation in the Upper Blue Nile River Basin of Ethiopia by using the Anjeni watershed as a case study site. Disturbed and undisturbed soil samples were collected from two sub‐watersheds of Anjeni: the Minchet sub‐watershed (with SWC measures) and the Zikrie sub‐watershed (without SWC measures). Soil samples were taken from 30‐cm depth from five representative landscape positions and analyzed following the standard soil lab analysis procedures. The results show that soils from the conserved sub‐watershed had improved quality indicators compared with those from the non‐conserved site. Significant improvement due to SWC measures was observed in the soil hydrological [total moisture content (+5·43%), field capacity (+5·35%), and available water capacity (+4·18%)] and chemical [cation exchange capacity (+4·40 cmol(+) kg−1), Mg2+ (+1·90 cmol(+) kg−1), Na+ (+0·10 cmol(+) kg−1)] properties. SWC interventions significantly reduced soil erosion by 57–81% and surface runoff by 19–50% in the conserved sub‐watershed. Reduction in soil erosion can maintain the soil organic carbon stock, reduce the land degradation risks, and enhance the C sequestration potential of soils. Therefore, adoption of SWC measures can increase farmers' ability to offset emissions and adapt to climate change. However, SWC measures that are both protective and sufficiently productive have not yet been implemented in the conserved sub‐watershed. Therefore, it is important that SWC structures be supplemented with other biological and agronomic measures in conjunction with soil fertility amendments appropriate to site‐specific conditions. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
A field experiment (1998 to 2010) investigated the effects of vermicompost (VC) and chemical fertilizer (CF) application alone or in combination on soil fertility status in arecanut. Vermicompost significantly increased the soil pH (6.3) over CF and integrated treatments (5.7–5.8). Greater soil organic carbon was noticed with VC (2.85–3.00%) than with CF (1.72–1.89%) and VC + CF (1.89–2.55%) in 2009. Soil test phosphorus (P) (mg kg–1) significantly increased with VC 200% nitrogen (N) equivalency (35.3) compared to other treatments (8.5–23.3) at the 0- to 30-cm depth in 2009. In 2003, soil test potassium (K) (mg kg–1) was significantly greater with CF at depths of both 0–30 cm (162–187) and 30–60 cm (172–214) than VC and control. Soil test K depleted with VC application in 2009. Application of VC significantly improved soil test calcium (Ca) and magnesium (Mg) compared to CF, CF + VC, and control at 0–30 cm deep. Soil test values for micronutrients increased in 2009 compared to initial status.  相似文献   

9.
The mountainous region of the Himalayas is covered with forest, grassland, and arable land, but the variation in ecosystem functions has not been fully explored because of the lack of available data. This study appraises the changes in soil properties over the course of a year (spring, summer, autumn, winter) for forest, grassland, and arable soils in a typical hilly and mountainous region of Azad Jammu and Kashmir, Pakistan. Soil samples were collected from major land-cover types in the mountain region: natural forest, grassland, and cultivated land (arable). The natural forest served as a control against which changes in soil properties resulting from removal of natural vegetation and cultivation of soil were assessed. Soil samples were collected from depths of 0–15 and 15–30 cm six times during the year and examined for changes in temperature, moisture, electrical conductivity (EC), micronutrients [iron, manganese, copper, and zinc (Fe, Mn, Cu, Zn, respectively)], and microbial population. Significant differences were found in soil temperature, soil moisture, Fe, Mn, Cu, Zn, and number of bacteria, actinomycetes, and fungi among the three land-cover types. Soil under cultivation had 4–5 °C higher temperature and 3–6% lower moisture than the adjacent soils under grassland and forest. Electrical conductivity (EC) values of forest, grassland, and arable soil were 0.36, 0.30, and 0.31 dS m?1, indicating that soil collected from the forest had 18–20% more EC than the adjacent arable and grassland soils. On average, amounts of Fe, Mn, Cu, and Zn in the soil collected from the arable site were 6.6, 5.7, 1.7, and 0.8 mg kg?1, compared with 24.0, 12.1, 3.5, and 1.2 mg kg?1 soil in the forest soil, showing that arable had two to four times less micronutrients than grassland and forest. Populations of bacteria, actinomycetes, and fungi in the forest were 22.3 (105), 8.2 (105), and 2.5 (103), respectively, while arable land exhibited 8.2 (105), 3.2 (105), and 0.87 (103). Season (temperature) and depth showed significant effects on microbial activity and nutrient concentration, and both decreased significantly in winter and in the subsurface layer of 15?30 cm. Different contents of the parameters among arable, grassland, and forest soils indicated an extractive effect of cultivation and agricultural practices on soil. Natural vegetation appeared to be a main contributor to soil quality as it maintained the moisture content and increased the nutrient status and microbial growth of soil. Therefore, it is important to sustain high-altitude ecosystems and reinstate the degraded lands in the mountain region.  相似文献   

10.
The effects of drip fertigation of NPK and vermicompost extract (VCE) on soil fertility status of arecanut-only and arecanut-cocoa systems were assessed in a 4-year field study. In arecanut, soil pH was reduced over initial levels. At 0–30 cm deep, fertigation of 75 percent NPK to arecanut only and organic-matter recycling in arecanut + cocoa maintained significantly greater soil organic carbon (SOC) and soil-test phosphorus (P). At the first depth, soil potassium (K) was significantly greater with 75 percent NPK (246 mg kg?1) than other treatments. In cocoa, soil pH varied significantly due to fertigation at both depths. The SOC was reduced due to 75 percent NPK at the first depth. In cocoa, the P availability increased significantly with application of VCE at 20 percent N. Fertigation of 75 percent NPK maintained significantly greater soil K and soil Mg than other treatments. The results suggest that drip fertigation of NPK sustains the soil fertility status in arecanut and cocoa.  相似文献   

11.
Temporal changes in soil chemical and nutritional properties were evaluated in a long-term experiment conducted on Alfisols in West Africa. Effects of land use and cropping duration on soil chemical properties at 0–5 cm and 5–10 cm depths were evaluated for five treatments: (1) alley cropping with Leucaena leucocephala established on the contour at 4-m intervals; (2) mucuna (Mucuna utilis) fallowing for 1 year followed by maize (Zea mays)-cowpea (Vigna unguiculata) cultivation for 2 years on severely degraded land; (3) fallowing with mucuna on moderately degraded soils; (4) ley farming involving growing improved pastures for 1 year, grazing for the second year, and growing maize-cowpea for the third year on severely degraded land; (5) ley farming on moderately degraded soils. Soil chemical properties were measured once every year from 1982 through 1986 during the dry season, and included pH, soil organic carbon (SOC), total soil nitrogen (TSN), Bray-P, exchangeable cations, and effective cation exchange capacity (CEC). Regardless of the cropping system treatments, soil chemical quality decreased with cultivation time. The rate of decrease at 0–5 cm depth was 0·23 units year−1 for pH, 0·05 per cent year−1 for SOC, 0·012 per cent year−1 for TSN, 0·49 cmol kg−1 year−1 for Ca2+, 0·03 cmol kg−1 year−1 for Mg2+, 0·018 cmol kg−1 year−1 for K+, and 0·48 cmol kg−1 year−1 for CEC. Although there was also a general decrease in soil chemical quality at 5–10 cm depth, the trends were not clearly defined. In contrast to the decrease in soil properties given above, there was an increase in concentration at 0–5 cm depth of total acidity with cultivation time at the rate of 0·62 cmol kg−1 year−1, and of Mn3+ concentration at the rate of 0·081 cmol kg−1 year−1. Continuous cropping also increased the concentration of Bray-P at 0–5 cm depth due to application of phosphatic fertilizer. Trends in soil chemical properties were not clearly defined with regards to cropping system treatments. In general, however, soil chemical properties were relatively favorable in ley farming and mucuna fallowing treatments imposed on moderately degraded soils. Results are discussed in terms of recommended rates of fertilizer use, in view of soil test values, expected yields, and critical limits of soil properties.  相似文献   

12.
ABSTRACT

Orchard efficiency (OE) is one of the indices of evaluating the sustainability in production behavior of citrus orchards. A wide range of soil properties broadly categorized into particle size distribution, water soluble and exchangeable cations, and soil available nutrients were investigated in relation to efficiency of Nagpur mandarin (Citrus reticulata Blanco) orchards established on smectite rich three soil orders (Entisols, Inceptisols, and Vertisols) representing 18 locations of central India. The soil properties, viz., free calcium carbonate (CaCO3), clay content, water soluble- and exchangeable-calcium (Ca2 +), available nitrogen (N), phosphorus (P), and zinc (Zn) contributed significantly towards variation in OE. The threshold limit of these limiting soil properties was further established using multivariate quadratic regression models as: 132.1 g kg? 1 free CaCO3, 418.1 g kg? 1 clay, 149.9 mg L? 1 water soluble Ca2 +, 25.9 cmol(p+) kg? 1 exchangeable Ca2 +, 114.6 mg kg? 1 available N, 12.8 mg kg? 1 available P, and 0.96 mg kg? 1 available Zn in relation to optimum OE of 82.1%. These reference values were very close to those obtained from best fit models, and could be effectively utilized in addressing soil related production constraints for precision-aided citriculture.  相似文献   

13.
Twenty acid soils of West Bengal, India, representing Alfisols, Entisols and Inceptisols orders, were studied to characterize their acidity in relation to physicochemical properties. Total potential acidity (TPA), pH-dependent acidity (PDA), total acidity (TA), hydrolytic acidity (HA) and exchange acidity (EA) ranged from 2.02–6.90, 1.75–6.05, 1.18–2.75, 0.98–1.90 and 0.06–0.85 cmol(p+) kg?1, respectively. Relative order for all forms of acidity was: Entisols>Alfisols>Inceptisols. Average contribution of EA to TPA and TA was 9.7% and 19.7%, respectively, and that of PDA to TPA was 90.1%. Contribution of electrostatically bound H+ to EA was highest for Inceptisols followed by Entisols>Alfisols, and reverse was true for electrostatically bound aluminum (Al3+). All forms of acidity showed significant positive correlations with organic carbon (C) forms of Al but negative correlations with pH of soil. They also showed significant correlations with each other. Soil pH, organic C and exchangeable Al caused most of the variations in different forms of soil acidity.  相似文献   

14.
A study on the long-term effect of fertilizers and amendments on crop productivity and changes in soil fertility in maize-wheat cropping system in an acid Alfisol was carried out in randomized block design (RBD) with 11 treatments. Continuous application of chemical fertilizers along with farmyard manure (FYM) or lime significantly influenced the grain and straw/stover yield and the uptake of nutrients by wheat and maize crops significantly. The organic carbon content increased from 7.9 to 12.1 g kg?1, cation exchange capacity (CEC) from 12.1 to 14.6 cmol (p+) kg?1 and available phosphorus from 21.9 to 75.2 kg ha?1 through the integrated use of organic and fertilizers for the last 42 years while the status of available nitrogen (N) and potassium (K) declined over the years in all the treatments. Continuous application of urea alone resulted in a drastic decline in soil pH at both depths. Imbalanced use of fertilizers led to a significant reduction in the productivity of both crops and depleted the soil fertility.  相似文献   

15.
Land degradation is a global problem. Best management of degraded land can be done by evaluating the spatial variability of soil properties including chemical properties of degraded land and mapping such variations. Since, a significant portion of arable land in India is chemically degraded due to soil acidity; the present study was conducted to study the spatial variability of soil acidity (pH), electrical conductivity (EC), soil organic carbon (OC) content, exchangeable potassium (K+), calcium (Ca2+) and magnesium (Mg2+) contents in some cropped acid soils of India. A total of four hundred (one hundred from each series) representative surface (0–0.15 m depth) soil samples were collected from arable soils representing four soil series namely Hariharapur, Debatoli, Rajpora and Neeleswaram situated in Orissa, Jharkhand, Himachal Pradesh and Kerala states of India, respectively, and were analyzed. Soil acidity (pH between 3.90 and 6.45) showed a low variability, in contrast to other soil properties, which showed moderate variability. The coefficients of variation varied from 32.4 to 74.3, 31.2 to 50.9, 45.6 to 100, 71.9 to 93.0 and 59.0 to 79.8% for EC (mean between 0.05 and 0.09 dS m−1), OC (mean between 0.29 to 1.86%), exchangeable K+ (mean between 39.1 and 77.7 mg kg−1), Ca2+ (mean between 148 and 293 mg kg−1) and Mg2+ (mean between 111 and 191 mg kg−1), respectively. Soil pH and OC content were positively and significantly correlated with exchangeable K+, Ca2+ and Mg2+ content. Geostatistical analysis revealed that the best fit models were gaussian, exponential and spherical for different soil properties with moderate to strong spatial dependency. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

16.
Tillage and soil management effects on soil physical and chemical qualities were monitored for eight years from 1979 through 1987 in a long-term experiment involving 17 consecutive crops of maize. Effects of no-till and plow-till methods of seedbed preparation were compared at two levels of residue management (residue removed versus residue returned) and two levels of fertilizer application (without fertilizer versus recommended fertilizer). Soil chemical quality was better for no-till compared with plow-till methods. Mean soil chemical properties of 0–5 cm depth for no-till and plow-till treatments respectively were 18·6 g kg−1 versus 12·2 g kg−1 for soil organic carbon content, 1·9 g kg−1 versus 1·1 g kg−1 for total soil nitrogen, 0·14 units yr−1 versus 0·18 units yr−1 rate of decline in soil pH, 63·1 mg kg−1 versus 31·8 mg kg−1 for Bray-P, and 6·0 cmol kg−1 versus 2·3 cmol kg−1 for Ca+2. Soil chemical quality consistently declined, although the rate of decline differed among tillage and fertilizer treatments. There were also differences in soil physical quality. Soil bulk density increased with cultivation duration in both tillage methods, and use of furadan in no-till plots drastically increased soil bulk density. Infiltration rate and soil moisture retention at all suctions was consistently more for no-till than plow-till treatments. Decline in soil quality with cultivation was reflected in decrease in crop yields. © 1998 John Wiley & Sons, Ltd.  相似文献   

17.
Abstract

Plantation establishment using exotic species on disturbed cultivated and undisturbed primary forest soils is common in Gambo district, southern Ethiopia, but their effects on soil properties are not fully known. This study investigated the effects of plantation species on major soil physical and chemical properties and further evaluated the soil quality under different land uses. Soil samples in triplicates, collected under different plantations, were analysed for their physical and chemical properties. Based on these soil properties, an integrated soil quality index was determined. The soil bulk density (BD) varied from 0.72 to 0.80 cm?3 in plantations established on primary forest land and natural forest and from 0.86 to 1.14 g cm?3 in those plantations established on cultivated soils. Also significantly lower pore volume and infiltration rate were observed under plantations established on cultivated lands than those on primary forest soils. Higher water volume (% at ?1500 kPa matric potential) was obtained in soils under Juniperus procera and natural forest compared with that under the rest of the plantations investigated. The concentration of soil organic carbon (SOC) varied from 3.4 to 10.2%, N from 0.3 to 1.0% and Av.P from 1.5 to 7.0% in soils under plantations and natural forest. Exchangeable cations generally showed a decreasing trend with depth in all land use types with minor exceptions. The concentrations of exchangeable Ca+2 varied from 6.5 to 22.7 cmol kg?1 and were significantly higher under Juniperus procera than under Eucalyptus species. The soil under plantations on previously cultivated lands showed soil quality index below 0.5 (the baseline value), while those established on undisturbed forest soil were generally above that value. The study results suggest that selecting species such as Juniperus procera and prolonging the harvesting period would improve and maintain the quality of soil properties.  相似文献   

18.
Litchi is one of the important subtropical fruit crops in the state of Jharkhand, occupying around 33,000 ha with production of about 165,000 metric tons. Considering the importance of soil analysis in litchi crops, the present investigation was carried out in an established orchard (begun in 1979) at the Horticulture and Agroforestry Research Program, Indian Council of Agriculture Research Complex for Eastern Region, Plandu (Ranchi), Jharkhand, India, to study the nutrient concentrations in soils of litchi and the interrelationships among available nutrient concentrations present in soil, and crop productivity in order to develop a sound fertilizer management program. Periodic collection of soil samples from the established orchard was carried out on the second week of every month during 2006–2007. Analysis of soil samples were carried out for macro- and micronutrients in soil. Mean soil nutrient contents for nitrogen (N), phosphorus (P), and potassium (K) were 232 kg ha?1, 53 kg ha?1, and 420 kg ha?1, respectively. The greatest contents of N and K were observed at full canopy distance, whereas for that for P was at one-third and two-thirds the canopy distance. Mean soil nutrient contents were 1.52 C mol (P+) kg?1, 1.11 C mol (P+) kg?1, and 23 ppm for calcium (Ca), magnesium (Mg), and sulfur (S), respectively. The greatest contents of Ca and Mg were observed at one-third the canopy distance whereas that for S was at two-thirds the canopy distance. However, mean soil nutrient contents were 1.03, 53, 65, and 1.42 ppm for copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), respectively. The greatest content of Fe was observed at two-thirds the canopy distance whereas that for Cu was at one-third the canopy distance. The greatest Mn content was observed for both two-thirds and full canopy distance whereas Zn contents had no significant differences among the canopy distances. However, soil sampling at two-thirds canopy distance from the trunk was observed to be ideal for soil analysis.  相似文献   

19.
Low soil fertility and soil acidity are among the major bottlenecks that limit agricultural productivity in the humid tropics. Soil management systems that enhance soil fertility and biological cycling of nutrients are crucial to sustain soil productivity. This study was, therefore, conducted to determine the effects of coffee‐husk biochar (0, 2.7, 5.4, and 16.2 g biochar kg?1 soil), rhizobium inoculation (with and without), and P fertilizer application (0 and 9 mg P kg?1 soil) on arbuscular mycorrhyzal fungi (AMF) root colonization, yield, P accumulation, and N2 fixation of soybean [Glycine max (L.) Merrill cv. Clark 63‐K] grown in a tropical Nitisol in Ethiopia. ANOVA showed that integrated application of biochar and P fertilizer significantly improved soil chemical properties, P accumulation, and seed yield. Compared to the seed yield of the control (without inoculation, P, and biochar), inoculation, together with 9 and 16.2 g biochar kg?1 soil gave more than two‐fold increment of seed yield and the highest total P accumulation (4.5 g plant?1). However, the highest AMF root colonization (80%) was obtained at 16.2 g biochar kg?1 soil without P and declined with application of 9 mg P kg?1 soil. The highest total N content (4.2 g plant?1) and N2 fixed (4.6 g plant?1) were obtained with inoculation, 9 mg P kg?1, and 16.2 g biochar kg?1 soil. However, the highest %N derived from the atmosphere (%Ndfa) (> 98%) did not significantly change between 5.4 and 16.2 g kg?1 soil biochar treatments at each level of inoculation and P addition. The improved soil chemical properties, seed yield, P accumulation and N2 fixation through combined use of biochar and P fertilizer suggest the importance of integrated use of biochar with P fertilizer to ensure that soybean crops are adequately supplied with P for nodulation and N2‐fixation in tropical acid soils for sustainable soybean production in the long term.  相似文献   

20.
Soil phosphorus (P) removal by harvest may be a practical remediation strategy. Small plots of bahia grass (BG) (Paspalum notatum Flügge), common bermuda grass (CB) (Cynodon dactylon (L.) Pers.), crab grass (CG) (Digitaria ciliaris (Retz.) Koel.), and switch grass (SG) (Panicum virgatum L.) were established on a coastal plain soil (Mehlich 3P, 100–500+ mg kg?1) . Yield, tissue P concentration, and uptake P were determined in 2002–2005, and surface (0–15 cm) soil P were determined in 2002 and 2005. The uptake decreased, SG > CG > BG = CB (range 230–90 kg ha?1), paralleling the decrease in surface soil P. Uptake depended on soil P (P < 0.01–0.10), with uptake > surface soil P decrease at low soil P due to uptake from subsoil but decrease > uptake at high soil P due to leaching. Soil P concentration did not affect SG tissue P nor did multiple harvests decrease its relative productivity.  相似文献   

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