Values Of Soil Organic Matter Research Articles

Effects of Vermicompost and Salinity on Proctor Optimum Water Content, Maximum Dry Bulk Density and Consistency of a Sandy Clay Loam Soil

ABSTRACT Salinity and sodicity greatly influences ongoing physical processes in soils. Organic matter may rehabilitate physical and mechanical properties of soils. Vermicompost as an amendment influences moisture-related parameters including consistency (plastic – PL and liquid limit – LL) and compaction. This study was conducted on soils (sandy-clay-loam) treated with different salinity levels (0.58 (control – irrigation water quality, tap water), 4 and 8 dS m−1) to investigate the effects of different vermicompost doses (0% (control), 2.5% and 5% w/w) on soil consistency limits and compaction. The pot experiment was carried out in a total of 27 pots, i.e. 3 (vermicompost doses) x 3 (salinity levels) x 3 (number of replicates). For Proctor compaction properties, maximum dry bulk density (MDD) reduced and optimum water contents (OWC) increased with increasing vermicompost doses under different salinity levels (p < .01). Increasing vermicompost doses under the lowest salinity level (0.58 dS m−1) yielded increasing optimum water contents for control (LL = 35.93% and PL = 25.85%). Optimum water contents were determined as 42.19% (LL) and 29.93% (PL) for 2.5% vermicompost dose and as 47.33% (LL) and 36.01% (PL) for 5% vermicompost dose under the lowest salinity level. LL, PL, OWC and MDD were significantly affected by vermicompost x salinity interactions. The highest maximum dry bulk density (1.92 g cm3) and the lowest optimum water contents (13.50%) were obtained from 0% vermicompost under the 8 dS m−1 NaCl level. Mean weight diameter (MWD) values ranged from 0.690 mm for 0% VC treatment under high Na salt level (8 dS m−1 NaCl) to 0.821 mm for 5% VC treatment under lowest Na salt level (0.58 dS m−1 NaCl). The correlations between aggregate stability (particle size group 1–2 mm) and optimum water content were 0.647*, 0.587* and 0.598* as compared to correlations of −0.512*, −0.470*, and −0.617** between aggregate stability (particle size group 1–2 mm) and maximum dry bulk density for the 0, 4 and 8 dS m−1 NaCl levels, respectively. MWD was positively correlated with OWC (0.386*) and negatively correlated with MDD (−0.385*). The greatest (2.39%) and the lowest (0.32%) soil organic matter values were respectively observed in 5% VC under the lowest salinity level (0.58 dS m−1) and 0% VC with at high Na salt level (8 dS m−1 NaCl). It was concluded that vermicompost reduced compaction-induced damage in soils.

Divergence in soil particulate and mineral-associated organic carbon reshapes carbon stabilization along an elevational gradient

Variations in climates and vegetation types along elevations in mountain ecosystems strongly reshape soil organic matter (SOM) stabilization. However, soil carbon (C) stabilization pathways from litter to SOM and potential mechanisms along elevations in the subalpine area remain unclear. Here, we investigated the C stabilization pathway from litter to particulate and mineral-associated organic matter (POM and MAOM) and associated drivers along elevational gradients in the Hengduan Mountains, China, based on δ13C signatures. Our results showed C stabilization pathways from litter to POM to MAOM, irrespective of elevation. Unexpectedly, the δ13C values of SOM and its fractions (POM and MAOM) were not significantly related to litter δ13C across elevations although litter was the main source of SOM, suggesting that other potential drivers could weaken the coordination of δ13C among litter and SOM fractions. We observed that the△13CLitter→POM (△13C between litter and POM) was more dependent on the direct effect of soil texture (i.e., sand, silt and clay). However, the △13CPOM→MAOM (△13C between POM and MAOM) was more related to microbial attributes (i.e., microbial community and enzyme activities).These results emphasizing the different stabilization procedures between POM and MAOM. Particularly, soil temperature dominantly determined △13CLitter→POM, but soil pH was the primary factor regulating the △13CPOM→MAOM. Overall, our results suggested that POM and MAOM formation occurred with different regulation processes, the POM formation was primarily via more physical pathways and MAOM formation mainly via more microbial pathways, thus providing novel insights into the better understanding of SOM formation and stabilization mechanisms in mountain ecosystems.

Soil Organic Matter and Soil Organic Carbon in Barito Delta

Soil organic matter and soil organic carbon is essential indication of soil carbon stock in terrestrial ecosystem particularly in peatland. Spatial distribution of soil organic carbon and soil organic matter is primary assessment to predict future soil condition under climate change traits. Barito Delta is one of peatland areas in Kalimantan Island that experiences urban expansion. It is necessary to assess distribution of soil organic carbon and soil organic matter to define the potential traits of urbanization and climate change to carbon stock condition in this delta. Therefore, the aim of this research is to analyze the distribution of soil organic matter and soil organic carbon in Barito Delta. Fieldwork measurement is performed to take sample of soil organic matter for each layer within 5 m soil depth. Inverse distance weighting interpolation is used to determine the spatial distribution of soil organic matter (SOM) and soil organic carbon (SOC) applying in R software.&#x0D; The value of SOM and SOC decrease along the increase of soil depth so that the largest percentage of SOM and SOC is in the first layer. Large value of SOM and SOC are mostly in the southern part of Barito Delta since it is bordered with sea water and downstream of rivers. The maximum value of SOM is ~12 % in the first layer, while 8.3 % of SOC in the first layer. Nevertheless, the value of SOC decrease in the near future, it is as indication Barito Delta contribute to carbon stock loss realizing to atmosphere that can rise greenhouse gasses and climate change.

Sequential loss-on-ignition as a simple method for evaluating the stability of soil organic matter under actual environmental conditions

Soil organic matter (SOM) is one of the largest carbon (C) reservoirs on Earth, and therefore its stability attracts a great deal of interest from the perspective of the global C cycle. This study examined the applicability of loss-on-ignition with a stepwise increase in temperature (SIT-LOI) of soil to evaluate the stability of SOM using soil samples having different organic matter (OM) and mineral contents and different mean residence times (MRTs) for SOM. The responses of SOM to the SIT-LOI varied depending on the samples but were all successfully approximated by a liner regression model as a function of the temperature of LOI. The slope value in the liner model that determines the residual potential of carbon during the SIT-LOI highly correlated with MRT of SOM, suggesting that this value reflects the overall stability of SOM over a range of soil properties. This hypothesis was consistent with the observation that Δ14C values of SOM decreased with increasing LOI temperature and thus, older, slower-cycling SOM was preferentially left in the soil samples by SIT-LOI. Additionally, the hypothesis was also supported by the significant correlations (p < 0.01) between the slope value and OM and mineral contents in the samples because these components are considered to regulate SOM stability. In addition to the regression analysis of the SIT-LOI data, changes in carbon to nitrogen (C/N) and carbon to hydrogen (C/H) ratios and stable carbon isotope signatures (δ13C) of the samples were investigated. The results suggest that the mineral association of SOM is an important factor characterizing the response of SOM to LOI. Hence, it was concluded that SIT-LOI is a simple and useful method for evaluating the stability of SOM under actual environmental conditions.

Assessment of Soil Fertility Status in Paroo and Saraiyan Blocks of Muzaffarpur District of Bihar Using GPS and GIS

The experiment was conducted during 2019‒21 at Paroo and Saraiya blocks of Muzaffarpur district of Bihar, India to identify the nutrients status for crop management. Soil fertility inventory research was carried out in these two identified blocks (Paroo and Saraiyan) for generation of thematic soil fertility map. For nutrient assessment altogether 40 (forty) geo-referenced composite soil samples were collected from the various locations of the studied area using a hand-held GARMIN GPS device. The processed soil samples were used for analysis of various soil fertility parameters by using prescribed standard methods. Soil nutrient status and fertility maps were created by using ArcGIS 10.4.1 software employing Inverse Distance Weighted (IDW) interpolation techniques. The results clearly indicated that the soils pH was alkaline in nature ranges from 7.4‒9.5. The mean value of Soil organic matter (0.55%) and potassium (150 to 250 kg ha-1) was found to be low to medium whereas, available nitrogen (119.9 to 319.1 kg ha-1) found 90% deficient, however, phosphorus (4.34 to 18.4 kg ha-1), and sulphur were recorded low in the blocks. However, most of the sample of micronutrients like copper (0.23 to 1.07 mg kg-1) and Iron (1.64 to 13.2 ppm) showed above critical limits while manganese, zinc deficiency were occurred in wide area. The intensive cropping system and imbalanced use of chemical fertilizer is degrading the soil quality in study area.

Impacts of shrubs on soil quality in the native Monte rangelands of Southwestern Buenos Aires, Argentina

AbstractShrub cover in semiarid rangelands may induce changes in soil resources and ecosystem functioning. However, it is unknown the real influence that shrub vegetation has on soil quality in rangelands used for livestock purposes. We evaluated the shrub cover effect on 12 chemical and biochemical parameters of soil quality. In a semiarid Monte rangeland of Argentina, 6 paddocks were selected and 10 m transects were placed in a patch with (Sh) and without shrubs (WSh). Then, sites with grasses (Sh‐G and WSh‐G), bare ground‐litter (Sh‐BL and WSh‐BL), and under shrub cover (Sh‐S) were selected. In spring 2017 and 2018, a composite soil sample (0–10 cm in depth) was taken at each site (n = 6). Sh‐G and Sh‐S sites presented high values of soil organic matter, soil organic nitrogen, particulate organic matter (POM), and cellulase activity (CA); WSh‐BL and Sh‐BL sites were associated with the lowest contents of these variables. For the rest of the soil quality parameters, the soil sampling sites showed similar values. These results show that woody presence should not be directly linked to soil quality loss. Although we did not detect a shrub effect in all parameters studied, in the context of appropriate grazing management, the presence of plant species of different functional groups has a positive effect on organic matter and N content of soil close to them. Moreover, in these sites, high POM values represent an important reservoir of potentially available nutrients, and promote CA necessary for fresh litter decomposition improving the soil quality of semiarid rangelands.

Soil organic matter in temperate forest-grassland systems: A case study from the Southern Cis-Ural, Russia

Understanding the dynamics of SOM in different land use types is critical for effective land management and climate mitigation strategies. In this study, we investigated the differences in soil organic matter (SOM) content between forest and grassland landscapes in the mountainous zone of Republic of Bashkortostan, Russia. We collected soil samples from multiple locations under both land use types and analysed them for SOM content using standard laboratory techniques. The results showed that the SOM content varied from 2.2 to 15.3% under forest landscape with an average of 6.7% and was characterized by high variability (51.8%). The SOM concentrations under grassland ranged from 2.1 to 6.5% with an average of 3.2%, while the coefficient of variation was 31.8%. According to the classification, the average SOM value in forest soils was classified as “high”, while in grassland soils it was classified as “low”. Overall, the variability in SOM content within forested landscapes can be influenced by a range of factors, including topography, erosion, and redeposition of soil. These factors contributed to the complex patterns of SOM accumulation and decomposition observed in forest soils, and should be considered when evaluating the potential impacts of land use change on SOM. Our study highlights the importance of understanding the factors that influence SOM content in soils, and the need for careful management of land use systems to maintain or enhance soil fertility and productivity.

Physico-chemical Properties and Heavy metal Contamination Levels of Soils from Riruwai Mining Area, North-western Nigeria

Mining activities, despite their economic importance, are well documented as one of the most significant sources of heavy metal pollution in the soil. In the present study, the physico-chemical properties and heavy metal contamination levels of the soils around the Riruwai mining area, in north-western Nigeria, were investigated. A total of 60 surface soil samples from four (4) sampling sites, which include 18 from active mine sites, 12 from abandoned mine sites, 21 from farmlands and 9 from control sites, were collected during the dry and rainy seasons. The physico-chemical properties such as pH, electrical conductivity (EC), soil organic matter (SOM), and cation exchange capacity (CEC) were determined using various analytical techniques. The concentrations of heavy metals were analyzed using a Microwave Plasma Atomic Emission Spectrometer (MP-AES), and the measured concentrations were used to evaluate the pollution load index (PLI). The findings of the study revealed that mining activities had a significant impact on the physicochemical characteristics of the soils, with lower pH, CEC, and SOM values in particular in active and abandoned mining sites. The physico-chemical characteristics of soil vary seasonally, with higher values typically reported during the rainy season, except for pH. The concentrations of arsenic, cadmium, lead, and zinc in the soils of the Riruwai mining area exceeded the threshold value recommended by WHO/FAO (2001) in all the sampling locations and seasons, with the exception of the control sites. The PLI values indicated that the soils in active and abandoned mining sites are strongly polluted by heavy metals, while farmland soils are moderately polluted and control site soils are unpolluted. The soils in the study area are significantly contaminated by heavy metals, particularly in active and abandoned mining sites, and the contamination has spread to farmland, suggesting a significant need for proper containment of heavy metal pollution levels in the area, particularly arsenic, cadmium, lead, and zinc.

Natural revegetation over ∼ 160 years alters carbon and nitrogen sequestration and stabilization in soil organic matter on the Loess Plateau of China

Natural revegetation has been reported to play a very active role in ecosystem carbon (C) and nitrogen (N) sinks in degenerated ecosystems. However, the responses of C and N sequestration and stabilization in soil organic matter (SOM) to natural revegetation remain inadequately understood. In this study, we analyzed C and N contents and δ13C and δ15N values of SOM, free light fraction (FLF), intra-aggregate particulate organic matter (IPOM) and mineral-associated organic matter (MAOM) along ∼ 160 years of natural revegetation on the Loess Plateau of China. The results showed that natural revegetation significantly (P < 0.05) enhanced soil C and N contents in FLF, IPOM, MAOM, SOM in the surface soil (0–20 cm) during the later stages of revegetation, which exhibited smaller impact on the deeper soil (20–60 cm). Natural revegetation significantly increased distribution proportions of C and N in FLF (i.e., 18.00–36.00%, 8.46–22.57%, respectively), and that in IPOM (i.e., from 11.60 to 25.38%, 10.89–26.92%, respectively), while it decreased that in MAOM (i.e., from 56.25 to 37.00%, 67.69–50.24%, respectively) in the surface soil, thereby altering C and N stabilization in SOM (0–20 cm). The climax Quercus liaotungensis forest exhibited the highest C distribution proportion in FLF and IPOM, and the lowest C distribution proportion in MAOM in the surface soil. The δ13C and δ15N were enriched with the decomposition of SOM and soil profile depths at each revegetation stage. The highest δ13C and δ15N values (0–60 cm) and the lowest C:N ratio (0–20 cm) of SOM, FLF, and IPOM were found in the farmland. In conclusion, ∼160 years of natural revegetation substantially promoted C and N sequestration in SOM, whereas altered C and N stabilization in SOM of the surface soil through shifting C and N towards more non-protected and pure physically protected SOM fractions rather than the most stable MAOM. Meanwhile, soil δ13C and δ15N in SOM and its fraction were changed along with natural revegetation. The most enriched soil δ15N in the farmland implied that soil N cycle in the farmland was more open to N losses relative to the other revegetation stages.

General trends of different inter-row vegetation management affecting vine vigor and grape quality across European vineyards

Cover crops in vineyards do provide many important ecosystem functions, however wine growers are often reluctant to incorporate cover crops into their vineyard management as they are concerned about competition regarding water and nutrient availability. The objective of this study was to define the effects of three standard inter-row vegetation management strategies on vine growth and grape quality in different European regions. We hypothesize that general patterns of responses to different inter-row management can be identified across European vine growing regions independent of local climate and soil conditions. Data were collected in 2016 and 2017 in commercial vineyards located in five European temperate wine growing regions directly comparing standard inter-row vegetation management strategies in parallel in vineyards ranging from cover crops to bare ground through tillage or herbicide application. Vegetation management strongly influenced leaf chlorophyll content, shoot pruning weight and yeast assimilable nitrogen (YAN) in grape juice. Across countries, grape varieties and varying soil conditions, YAN consistently showed higher values in grapes separated by bare ground inter-rows as compared to inter-rows with a permanent vegetation cover. Other grape quality parameters, total soluble solids, total titratable acidity and berry weight were not or inconsistently affected across countries, preventing the prediction of generalized trends. We also observed higher values of soil organic matter in complete vegetation inter-rows. In conclusion, we identified general effects of inter-row vegetation management on vine vigor and grape quality across countries and grape varieties in different pedo-climatic conditions. Our study provides general response patterns as a basis for functional studies to develop local inter-row vegetation management strategies.

Combining different pre-processing and multivariate methods for prediction of soil organic matter by near infrared spectroscopy (NIRS) in Southern Brazil

In Brazil, most guidelines for soil nitrogen (N) fertilization are based on the soil organic matter (SOM) content, which is one of the most laborious and expensive parameters in routine soil analysis. Recently, several studies have been made to generate and evaluate alternative methods to estimate SOM content, such as those based on near infrared spectroscopy (NIRS). However, the accuracy of NIRS is highly affected by spectral pre-processing techniques and multivariate methods. Moreover, the models are highly site-specific, indicating the need to develop regional calibrations. The objective of this study was to evaluate the effect of pre-processing and multivariate methods in SOM prediction using NIRS. A total of 2388 soil samples from Southern Brazil were analyzed for SOM content by carbon oxidation with a sulfochromic solution, followed by spectrophotometric colorimeter determination (modified Walkley-Black method) and by a NIR-spectrometer (1200–2400 nm). Seven pre-processing techniques were tested, including: Savitzki-Golay derivative (SGD), continuum removal (CR), detrend (DET), binning (BIN), smoothing (SMO), and the standard normal variate (SNV). The pre-processing techniques were combined with four multivariate models including multiple linear regression (MLR), partial least squares regression (PLSR), principal component regression (PCR), support vector machine (SVM), random forest (RF) and gaussian process regression (GPR). The performance of the predictions was evaluated by the coefficient of determination (R2) and the root mean squared error (RMSE). Moreover, SOM predictions obtained from the models were compared with the wet digestion method in order to evaluate the capability to correctly classify the SOM content for N fertilization. Overall, comparing the multivariate models, the best predictions according to R2 were found for SVM > GPR > PLSR > MLR > PCR > RF, in decreasing order. The best prediction was obtained with the combination of SVM model and SNV spectral pre-processing (R2 = 0.70, RMSE = 0.44, RPIQ = 2.26). For SVM and GPR, only DET, SNV, BIN and CR improved predictions when compared to raw spectra. When using the linear model MLR, the prediction of SOM was improved only with SNV, SMO and DET, compared to raw spectra. For the PLSR model, the prediction of SOM was improved with DET and SNV. Results estimated by NIRS reached 85% accuracy when compared to values of SOM obtained by the modified Walkley-Black method.

Evaluation of pedotransfer functions for predicting particle density of soils with low organic matter contents

Soil particle density (ρs) is a basic soil physical property which is essential for soil pore volume estimation and sediment source discrimination. The measurement of soil ρs is labor intensive and time-consuming. Pedotransfer functions (PTFs) have been developed for estimating ρs from readily available soil properties during the past decades. Existing PTFs are developed mainly based on soil datasets covering wide ranges of soil organic matter (SOM) contents. For soils from subtropical regions with low SOM values the accuracy of previous PTFs remains unknown. In this study we evaluated the performance of existing ρs PTFs by comparing model estimates to measurements of 175 soils from a subtropical region in China. The investigated soils had relatively low SOM contents (mostly<0.02 g g−1) and covered texture ranges from coarse sand to clayey soils. The Adams-based PTFs performed poorly, while the modified Adams PTFs and several simple linear or multiple regression PTFs produced relatively accurate ρs estimates for the 175 soils with root mean square errors (RMSEs) around 0.05 g cm−3 and mean biases within ± 0.03 g cm−3. Further multiple regressions indicated that the ρs of subtropical soils was simply a negative linear function of clay content. Despite conflicting several early reports, an independent dataset showed that the proposed linear model provided accurate ρs estimates for soils with low SOM contents from subtropical regions with a RMSE of 0.030 g cm−3 and mean bias of −0.013 g cm−3.

Land Use Effect on Quality of Plateau Soils: A Case Study of Ososo in Northern Edo State, Nigeria

The study examined land use effect on quality of plateau soils, using Ososo in Northern Edo State, Nigeria as a case study. The objectives were to examine the status of soils under the different land uses and evaluate variation in the physicochemical properties of soils among the investigated sites. A total of thirty-six soil samples were collected from secondary forest, cocoa plantation and quarry site at 0 - 15 and 15 - 30 cm depths. Soil quality indicators were analyzed in the laboratory, while data were examined by descriptive and inferential statistics. Due to the effect of mining activities, quarry site had lower mean values of soil organic matter, total organic carbon, total nitrogen, available phosphorous, effective cation exchange capacity, potassium, copper and manganese while iron, zinc and calcium were lower in secondary forest. However, Na and ECEC were higher in cocoa plantation. The study further revealed that though the examined land uses had varied effects on the soil properties; quarry site impacted the soil quality parameters more negatively compared to the secondary forest and cocoa plantation land use types. Significant variation (p &lt; 0.05) in sand, clay and available phosphorous was detected in the topsoil of the different land uses. The research concluded that the status of the soil nutrients was low. To improve the quality of the plateau soils, liming and the use of animal droppings, town refuse ash and plant remains is recommended.

Dynamics of organic matter in soils formed on limestone and sandstone in the karst area in southwestern China: δ 13C and δ 15N approaches

To better understand biogeochemical processes associated with the dynamics of soil organic matter (SOM), the δ 13C and δ 15N values were analyzed in the SOM of limestone soil (developed on limestone) and sandstone soil (developed on sandstone), as well as in dominant plant species and litter samples collected on the studied soil profiles in karst areas of Southwest China. In general, the content of soil organic carbon (SOC) and soil organic nitrogen (SON) is highest in the surface soil layer and decreases downward in both types of soil profiles. In addition, the content of SOM (including both SOC and SON) in the limestone is much higher than in sandstone soil. The higher pH values, as well as the content of calcium, magnesium, and clay minerals, are probably the reasons for the higher SOM content in the limestone soil compared to the sandstone soil.In the SOM of the upper layers of yellow sandstone and limestone soil δ 13C values range from 2.6‰ to 6.3‰ and δ 15N values from 5.1‰ to 8.1‰, which is larger than in litters. Yellow sandstone soils have smaller differences between δ 13C and δ 15N values of SOM from litter and topsoil than the limestone soil. The δ 13C and δ 15N values of SOM increase with depth in yellow sandstone soil profiles, but not in the limestone soil profiles. An increase in the values of δ 13C and δ 15N with a decrease in the SOM content in the yellow sandstone soil significantly substantiates the decomposition of SOM, which causes higher values of δ 13C and δ 15N values in the deeper soil horizons. By contrast, the limestone soil has complex depth profiles of δ 13C and δ15N, which can be mainly attributed to land-use changes and organic and mineral interactions between soil accumulations.

Incorporation of hydrogen from ambient water into the C-bonded H pool during litter decomposition

Aridity was observed to affect the C-bonded stable H isotope ratios (δ2Hn values) of aboveground plant organic matter but not δ2Hn values of associated soil organic matter (SOM). Instead, δ2Hn values of SOM correlated spatially with long-term mean δ2H values of local rainfall. To explain this discrepancy, we investigated if and to which degree C-bonded H was replaced by ambient water-H during leaf litter decomposition in laboratory microcosms.In a four-week incubation of leaf litter (Fagus sylvatical. - beech,Acer pseudoplatanusl. - maple) with two H-isotopically labeled waters (δ2Hiw: +50‰, +250‰), we found a small incorporation of isotopically labeled H into the C-bonded H pool (<5% of total C-bonded H) in beech litter. For the leached, more reactive total organic matter in solution (TOM), we estimated that 8–9% of C-bonded H was replaced by the isotope label during incubation. We suggest that the small incorporation of H from ambient water can be attributed to microbial processes.However, the small incorporation of H from ambient water during microbial processing would not be sufficient to overprint the aridity signal present in plant organic matter and shift δ2Hn values of SOM towards those of long-term rainfall. This supports the suggestion, that SOM originates from belowground sources including roots and microorganisms, which inherently show δ2Hn values related with those of long-term rainfall.

Evaluation of some selected soil properties of a drip irrigated tomato field at different moisture regimes in South-Western Nigeria

Soil properties are important to the development of agricultural crops. This study determined some selected soil properties of a drip irrigated tomato (Lycopersicon esculentum M.) field at different moisture regime in South-Western Nigeria. The experiment was carried out using Randomized Complete Block Design with frequency and depth of irrigation application as the main plot and sub-plot, respectively in three replicates. Three frequencies (7, 5 and 3 days) and three depths equivalent to 100, 75 and 50% of water requirement were used. Undisturbed and disturbed soil samples were collected from 0-5, 5-10, 10-20 and 20-30 cm soil layers for the determination of some soil properties (soil texture, organic matter content, bulk density, infiltration rate and saturated hydraulic conductivity) were determined using standard formulae. Soil Water Content (SWC) monitoring was conducted every two days using a gravimetric technique. The soil texture was sandy loam for all the soil depths; average value of soil organic matter was highest (1.8%) in the 0-5 cm surface layer and decreased with soil depth; the soil bulk density value before and after irrigation experiment ranged from 1.48 and 1.73 g/cm3 and 1.5 and 1.76 g/cm3, respectively; there was a rapid reduction in the initial infiltration and final infiltration rate. Saturated hydraulic conductivity show similar trend although the 20-30 cm layer had the lowest value (50.84 mm/h); the SWC affect bulk density during the growing season. The study showed that soil properties especially bulk density and organic matter content affect irrigation water movement at different depth..

Effects of Rice Husk Compost on Some Soil Properties, Water Use Efficiency and Tomato (Solanum lycopersicum L.) Yield under Greenhouse and Field Conditions

ABSTRACT The effect of rice husk compost (RHC) on some soil properties, evapotranspiration (ETa), yield (Y) and water use efficiency (WUE) of tomato (Solanum lycopersicum L.) plant under the field and greenhouse conditions was investigated. In the experiments carried out at the experimental field and the greenhouse of Agricultural Faculty in Ondokuz Mayıs University, Samsun, Turkey. The RHC was applied to surface soil (0–20 cm) at 0%, 3%, 6% and 9% (0 – 6 – 12 – 18 Mg ha−1) doses with three replications according to the randomized plots experimental design. RHC application generally improved the soil quality parameters according to the control treatment during the experiment carried out with growing tomato plant in the field and greenhouse conditions. RHC treatments increased electrical conductivity, field capacity and permanent wilting point, available water content with increasing soil organic matter content, reduced soil pH and bulk density (Db) over the control treatment. Db values of the soils in the field and greenhouse decreased according to the control treatment with 3% > 6% > 9% doses of RHC. Field capacity, permanent wilting point and available water capacity (AWC) values of the soils generally increased according to the control with 9% > 6% > 3% doses of RHC application. While 92-day ETa values in field ranged from 426 mm in control to 314 mm in 9% RHC application, 112-day ETa values in greenhouse ranged from 547 mm in control to 375 mm in 3% RHC application. According to the control treatment, the highest reduction in ETa values was 26.3% with 9% RHC in the field and 31.5% with 3% RHC application in the greenhouse. Soil organic matter values of the soils had significant correlations with Db (−0.868**), AWC (0.667*), yield (0.593*) and WUE (0.722**) in the greenhouse conditions and with Db (−0.628**), AWC (0.427*), yield (0.468*) in the field conditions. While there were negative relationships between WUE and ETa in field (−0.818**) and greenhouse (−0.365) conditions, the positive relationships between yield and WUE were determined in field (0.280) and greenhouse (0.887**). When comparing the control treatments, RHC applications in field and greenhouse conditions helped to water saving as 118 mm (1181 ton ha−1) and 216 mm (2160 ton ha−1), respectively. According to the results, the applications of 6% RHC in field and 9% RHC in greenhouse conditions were suggested to reduce ETa values, and to improve the soil quality parameters, WUE and tomato yield.

Ecological value of soil organic matter (mandala customary forests with awiq-awiq management)

The current ecological value has become a global trend that can be used as a reference in conservation. Soil is one of the parameters of the ecological value that stores organic matter (SOM) consists of organic elements C, N, P, and K contributing to the biogeochemical cycle. The purpose of this study is to determine the ecological value of soil organic matter in Mandala customary forests that is managed by using awiq-awiq. Data on soil organic matter content was carried out in the customary forests of Mandala, Bayan, West Nusa Tenggara, Indonesia. Soil samples taken at five points based on the height of 310-350 masl. Measurements were carried out directly and indirectly, using soil physical and chemical laboratory tests. Lab test results were then analysed using a cost-based approach to determine their ecological value. The results showed ecological values based on C, N, P and K (SOM) content of land contributed around 5609.74 USD / ha or 78,990,748, 9 IDR / ha and 5830.82 USD / ha or 82,103,776.4 IDR / ha. This value is an award given to Mandala customary forests in protecting SOM to maintain a biogeochemical cycle in forest ecosystems. However, it’s protection requires sustainable forest management.

Effect of soil nutrient spatial heterogeneity by cutting disturbance on understory plant diversity in broadleaved-Korean pine forest in Changbai Mountain, China

The spatial variation of forest soil nutrients influences the species composition, distribution and diversity of forest plants, because soil nutrients are the most important environmental factors limiting the growth and survival of plants. We analyzed the effect of the spatial heterogeneity of soil nutrients on understory vegetation diversity in broadleaved-Korean pine forest, which had been undergone cutting disturbance. The results are of great significance in the sustainable management of the broadleaved-Korean pine forest and understanding the mechanism of correlation between heterogeneity and diversity. We sampled four plots of broadleaved-Korean pine forest in Jiaohe Forestry Bureau in Jilin province, China. Plot A, a control, was unlogged broadleaved-Korean pine forest. In plot B, C and D, forest was cut at 20%, 35% and 55% of the intensity in 2011. Cutting intensity influenced significantly on total nitrogen (TN), total phosphorous (TP), pH, soil organic matter (SOM), nitrate nitrogen (NN) and ammoniacal nitrogen except total potassium (p < 0.05). The values of TN, TP, pH and SOM showed that their quantities could decrease as cutting intensity increased. Species richness and diversity index of woody plants could increase in proportion to the cutting intensity, but species richness and diversity index of herbaceous plants might tend to decrease in early spring and summer. Coefficient of variation of TN, TP, SOM and NN could have either a positive or negative correlation with α-diversity indices of woody and herbaceous plants, while the other soil nutrient indices could have no correlation with diversity indices.

In-situ soil greenhouse gas fluxes under different cryptogamic covers in maritime Antarctica

Soils can influence climate by sequestering or emitting greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). We are far from understanding the direct influence of cryptogamic covers on soil GHG fluxes, particularly in areas free of potential anthropogenic confounding factors.We assessed the role of well-developed cryptogamic covers in soil attributes, as well as in the in-situ exchange of GHG between Antarctic soils and the atmosphere during the austral summer. We found lower values of soil organic matter, total organic carbon, and total nitrogen in bare areas than in soils covered by mosses and, particularly, lichens. These differences, together with concomitant decreases and increases in soil temperature and moisture, respectively, resulted in increases in in-situ CO2 emission (i.e. ecosystem respiration) and decreases in CH4 uptake but no significant changes in N2O fluxes. We found consistent linear positive and negative relationships between soil attributes (i.e. soil organic matter, total organic carbon and total nitrogen) and CO2 emissions and CH4 uptake, respectively, and polynomial relationships between these soil attributes and net N2O fluxes.Our results indicate that any increase in the area occupied by cryptogams in terrestrial Antarctic ecosystems (due to increased growing season and increasingly warming conditions) will likely result in parallel increases in soil fertility as well as in an enhanced capacity to emit CO2 and a decreased capacity to uptake CH4. Such changes, unless offset by parallel C uptake processes, would represent a paradigmatic example of a positive climate change feedback. Further, we show that the fate of these terrestrial ecosystems under future climate scenarios, as well as their capacity to exchange GHG with the atmosphere might depend on the relative ability of different aboveground cryptogams to thrive under the new conditions.