تعیین مهمترین ویژگیهای خاکی موثر بر عملکرد زعفران در منطقة قاینات

The rehabilitation of sandy desertified land in various dryland ecosystems by different management practices has a great potential to increase aggregate stability and improve soil quality. However, plants in general may have a different ability to sustain soil. The objective was to determine the effects of reclamation practices including Haloxylon ammodendron and Atriplex canescens plantation on some soil properties, soil erodibility and the relationships among soil properties and erodibility index in desertified land of Jupar in Kerman province, southern Iran. According to the research objectives, 24 soil samples from 0-20 cm depth were taken from each area, i.e. reclamation sites and control area (untreated land) by systematic – random method. Soil properties such as soil texture, structure, pH, EC, CaCO3, gypsum, bulk density, organic carbon and soil organic matter were measured. The mean weight diameter (MWD) and geometric mean diameter (GMD) were used as soil erodibility indices. The results of our study showed that MWD had positive correlation with organic carbon, CaCO3 and soil acidity values. Furthermore, according to the effect of Haloxylon on aggregate stability and its positive role in modifying soil physical and chemical properties, and also the height of this species, which can contribute in wind erosion control in this area, therefore, it is concluded that Haloxylon ammodendron had better performance in desert rehabilitation project and to stabilize sandy land in Jupar area than Atriplex canescens.

Biochar, compost and biochar-compost: effects on crop performance, soil quality and greenhouse gas emissions in tropical agricultural soils

Investigations on temporal and spatial variation of slope-scale SOC erosion and deposition

<p>This study examined the impacts of land use on the physical and chemical properties of soils of land use types along agroforestry and agricultural landscapes in a rainforest zone of Nigeria. The land use systems are forest, agroforestry, fallow, and ornamental plant fields in addition to permanent crop fields (cocoa, oil palm, and citrus) and annual crop fields (maize). Profile pits were dug on the land use types and samples were collected 0–20 cm and 20–50 cm for laboratory analysis. Soil samples were collected from undisturbed soil and profile pits for bulk density and moisture content determination following standard analytical procedures. Among the land use types, physical properties (sand, clay, soil bulk density) and chemical properties (soil pH, SOC, total N, P, K, Ca, Mg, and CEC) differed significantly. Bulk density, pH, SOC, total, and stocks of SOC and N differed statistically for 0–20 and 20–50 cm soil depths with downward increases in N and SOC stocks along sampling depth. Permanent croplands (forest and agroforestry fields) had higher soil pH, SOC, total N, and CEC, while arable crop fields had relatively lower pH, SOC, TN, P, K, Ca, Mg, and CEC. Arable fields had significantly lower C and N stocks within 50 cm compared with permanent crop fields, which may be attributed to continuous tillage by the smallholder farmers and soil erosion-enhanced SOC and N removal from top soil. For both permanent and annual crop fields, SOC and total N stocks ranged from 5.75 to 3.12 kg/m<sup>2</sup> for 0–20 cm depths and 2.44 to 1.93 kg/m<sup>2</sup> for deeper (20–50 cm) layers. Relative to forest soil, stocks of SOC in the surface soils (0–20 cm) decreased in the order: agroforestry > ornamental plant field > cocoa > fallow land > citrus > oil palm > annual cropping system. Following this decreasing order, soil deterioration indices are equivalent to 27% > 28% > 30% > 31% > 32% > 34% > 38% compared with forest soil, respectively. Strong significant correlations (<i>p</i> < 0.05) were observed between SOC and TN stocks and some soil properties (bulk density, clay contents, pH, and CEC) with R<sup>2</sup> values ranging from 1.0 to 0.85. It is concluded that the soil's physical and chemical properties and carbon storage potential differed among the land uses of the study site.</p>

Deforestation and land-use effects on soil degradation and rehabilitation in western Nigeria. I. Soil physical and hydrological properties

Land‐use change affects many soil properties, including soil organic carbon (SOC) pool, and the transfer of atmospheric CO 2 to terrestrial landscapes. The objective of this study was to evaluate the effects of converting pastureland to Australian pine ( Casuarina spp ) and Black locust ( Robinia pseudoacacia L) forest on selected soil physical and chemical properties and SOC sequestration in reclaimed minesoils (RMS) of southeastern Ohio. The study sites were surface mined for coal, reclaimed and managed as pasture, and then converted into woodland 10 yr before the present study. Soil pH and electrical conductivity (EC) were higher in the RMS than in a nearby undisturbed hardwood forest. Conversion to Australian pine decreased soil pH and EC in the top 20 cm. Bulk densities of the RMS ranged from 1.24 to 1.82 Mg m −3 , and only minor changes were observed in soil bulk density after land‐use conversion. Mean weight diameter (MWD) and root biomass increased significantly ( P < 0.05) with conversion of pasture to Australian pine or Black locust. In addition, aggregate stability was greater in RMS under hardwood forest than under pasture. Conversion to the Australian pine forest increased the SOC pool in the top 50 cm by 6 Mg ha −1 (11%) in 10 yr. However, the N pool in the top 50 cm was not affected by the land‐use conversion from pasture to Australian pine. Conversion to Black locust increased the SOC pool in the top 50 cm by 24 Mg ha −1 (42%), while the N pool increased by 10% under Black locust in 10 yr. The increase in the SOC pool was accompanied by an increase in the C/N ratios and root biomass in both Australian pine and Black locust sites in the 20‐ to 50‐cm depth. Establishment of tree plantation has a greater potential for SOC sequestration than pastures in the RMS.

Characteristics and problems of marginal soils from acid sedimentary rocks in Kalimantan Marginal or suboptimal soils are potential for agricultural development such as food crops, estate crops, and industrial planted forest. These soils have low fertility status and susceptible to erosion. In Kalimantan, the marginal soils cover about 30.15 million ha or 57.22% of the total island area, with the major soils consist of Ultisols, few Oxisols, and Inceptisols. The physical properties of marginal soils from acid sedimentary rock are mostly influenced by the type of parent materials ( sandstone or claystone ) , while the chemical properties showed the similar characteristics indicating acid soil reaction, vary in organic matter, and low in cation exchange capacity, exchangeable bases, base saturation, mineral reserve, as well as P and K potentials, but the Al saturation is high. Agricultural development on these soils, other than the physical and chemical properties, should consider the relief condition. The areas with flat to undulating relief are recommended for perennial or food crops, while the annual or estate crops and industrial planted forest can be developed until the hilly area. Land management such as fertilization to improve nutrient status, liming to increase soil reaction and to decrease Al reactivity, and soil conservation practice were recommended. In this time, most of the marginal soils were utilized for estate crops development, such as oil palm, rubber, pepper, and industrial planted forest, and only a limited area for food crops. Keywords: Marginal soil, acid sedimentary rock, Ultisols, Oxisols, Inceptisols, Kalimantan

Soil microorganisms play crucial roles in nutrient cycling and determining soil quality and fertility; thus, they are important for agricultural production. However, the impacts of long-term fertilization on soil microbial community remain ambiguous due to inconsistent results from different studies. The objective of this study was to characterize changes in bacterial and fungal diversity and community structures after 12 years of different fertilization in aeolian sandy soil by analyzing 16S rRNA and ITS rRNA gene sequences and the soil properties to discover the driving factors. Eight different fertilizer treatments have been set up since 2009: no fertilizer (CK), chemical N fertilizer (N), chemical N and P fertilizer (NP), chemical N, P and K fertilizer (NPK), pig manure only (M), pig manure plus chemical N fertilizer (MN), pig manure plus chemical N and P fertilizer (MNP), pig manure plus chemical N, P, and K fertilizer (MNPK). The results indicated that the long-term application of chemical fertilizer reduced soil pH, whereas the addition of pig manure alleviated a decrease in soil pH value. Chemical fertilizer plus pig manure significantly improved soil available nutrients and soil organic carbon. Long-term MNPK fertilization resulted in changes in bacterial diversity due to effects on specific bacterial species; by contrast, all fertilization treatments resulted in changes in fungal diversity due to changes in soil properties. Principal component analysis indicated that fertilization had a significant effect on soil microbial community structure, and the effect of chemical fertilizer combined with pig manure was greater than that of chemical fertilizer alone. Soil available phosphorus, total phosphorus, and pH were the most important factors that influenced bacterial taxa, whereas soil pH, total phosphorus, organic carbon, ammonium nitrogen and nitrate nitrogen were the most important factors influencing fungal taxa after 12 years of fertilization in aeolian sandy soil.

Organic wastes have a positive impact on soil physical and chemical properties in the agroecosystems. However, its main effects on soil organic carbon (SOC) or total organic carbon, TOC (SOC and coal-C) contents as well as their effects on soil physico-chemical properties are still unclear. Two types of organic wastes (maize straw and manure) were utilized in dryland affected by mining activities to quantify their relative effect on soil physico-chemical properties. Regression analysis was used to assess the relationship between the soil physical properties, SOC, and TOC as well as their respective contributions to improving these properties. Treatments included control (CK), straw (S), low manure (LM), medium manure plus straw (S-MM), and high manure plus straw (S-HM). The results showed that SOC, soil bulk density, mean weight diameter (MWD), soil total porosity, soil penetration resistance, saturated hydraulic conductivity, and soil infiltration rate were strongly influenced by the application of organic wastes. A stronger linear relationship between SOC and the MWD, (R2 = 0.93, p < 0.05) compared to that between TOC and MWD indicated the important role of SOC in improving soil aggregation relative to the effect of TOC. According to the principal component analysis (PCA), the application of organic wastes had stronger effects on SOC contents and physical properties than TOC (SOC and coal-C). These findings advance our understanding of the actual effect of organic wastes on soil physical properties and SOC in dryland affected by mining activities and could inform fertilizer management decisions to improve soil properties.

Soil properties and organic carbon distribution under different land uses in reclaimed sodic soils of North-West India

Alpine grassland of the Tibetan Plateau has undergone severe degradation, even desertification. However, several questions remain to be answered, especially the response mechanisms of vegetation biomass to soil properties. In this study, an experiment on degradation gradients was conducted in an alpine meadow at the Zoige Plateau in 2017. Both vegetation characteristics and soil properties were observed during the peak season of plant growth. The classification and regression tree model (CART) and structural equation modelling (SEM) were applied to screen the main factors that govern the vegetation dynamics and explore the interaction of these screened factors. Both aboveground biomass (AGB) and belowground biomass (BGB) experienced a remarkable decrease along the degradation gradients. All soil properties experienced significant variations along the degradation gradients at the 0.05 significance level. Soil physical and chemical properties explained 54.78% of the variation in vegetation biomass along the degradation gradients. AGB was mainly influenced by soil water content (SWC), soil bulk density (SBD), soil organic carbon (SOC), soil total nitrogen (STN), and pH. Soil available nitrogen (SAN), SOC and pH, had significant influence on BGB. Most soil properties had positive effects on AGB and BGB, while SBD and pH had a slightly negative effect on AGB and BGB. The correlations of SWC with AGB and BGB were relatively less significant than those of other soil properties. Our results highlighted that the soil properties played important roles in regulating vegetation dynamics along the degradation gradients and that SWC is not the main factor limiting plant growth in the humid Zoige region. Our results can provide guidance for the restoration and improvement of degraded alpine grasslands on the Tibetan Plateau.

Rice (Oryza sativa L.)-wheat (Triticum aestivum L.) a dominant cropping system in Punjab Region, Northwestern India, overtime is believed to have negative effect on the soil and water quality. The present study was conducted in an ongoing long-term experiment at the research farm of the School of Organic Farming, Punjab Agricultural University, Ludhiana, to compare the effect of different cropping systems on soil physico-chemical properties. Ten treatments (cropping systems) were laid in a Randomized Complete Block Design (RCBD). The treatments were rice-wheat (CS1), maize-wheat (CS2), basmati rice-wheat-cowpea green manure (CS3), maize-mustard-cowpea green manure (CS4), maize-potato-spring groundnut (CS5), maize-peas-spring groundnut (CS6), maize+ cowpea (fodder)-maize fodder-oats fodder-sathi maize fodder (CS7), sorghum multicut fodder-barseem fodder (CS8), maize (cobs/fodder)-potato-onion (CS9), and baby corn-potato-okra (CS10). Soil samples were collected from four soil depths (0-7.5, 7.5-15, 15-22.5, and 22.5-30 cm) under each cropping system and analyzed for particles size, soil pH, EC, soil organic carbon, aggregate associated carbon, bulk density, porosity, water stable aggregates, MWD, and penetration resistance. Significantly lower soil pH was reported in CS4 and CS8 compared to other cropping systems. Soil EC was significantly higher in CS5 and CS10 while lowest in CS4. Soil organic carbon (SOC), aggregate-associated carbon (AAC), and mean weight diameter (MWD) were significantly higher in CS7 and CS4. Soil bulk density (BD) and penetration resistance (PR) were significantly higher in CS1 and lowest in CS4. SOC was 19% higher in CS7 and BD was 16% lower in CS4 compared to CS1. Soil porosity and water-stable aggregates (WSA) were also found significantly higher in CS4 and CS7 whereas lowest in CS1. The increase in soil depths significantly increased the soil pH, BD and PR, whereas decreased the soil EC, SOC, AAC, porosity, MWD, and WSA. The cropping systems (CS4, CS7, CS8, CS6, CS5, CS3) with green manure/legume/fodder crops in rotation resulted in better physico-chemical properties through the addition of organic matter to the soil compared to cereal-cereal rotations.

ABSTRACTThe objective of this study was to determine the influence of tillage methods (conventional tillage (CT) and minimum tillage (MT)) and N rates (0, 50, 150, 250 kg N ha−1) on crop yield, N uptake and soil organic carbon (SOC), bulk density (BD), total N (TN), electrical conductivity (EC), pH and soil nutrient contents on a clay-loam near Hashtgerd, Iran. A successive corn-based rotation (2012–2014) was conducted as a split-plot in a randomized complete block design in which tillage methods were considered as main plots, and N rates as subplots. Tillage had no significant effect on corn 2012 and canola 2012–2013 grain yields. CT and MT systems showed different critical N rates to reach their maximum grain yield in corn (2013) and wheat (2013–2014). MT system required more N application to reach its maximum grain yield. Tillage × N rate effect on none of the soil properties was significant. Tillage had no significant (P ≤ 0.05) effect on soil pH, BD, TN and SOC. However, soil EC of 0–5 cm depth in MT system was higher than CT system by 64%. MT system under higher N application could increase corn grain yield, but on the other hand probably adversely changes soil chemical properties.

The potential of using flue gas desulfurization by‐products (FGD) for the reclamation of acid minespoil was assessed in Tuscarawas County of Ohio, USA. In Treatment 1, 280 Mg ha −1 of FGD was incorporated into the graded spoil to a depth of 20 cm. In Treatment 2, 280 Mg ha −1 of FGD and 112 Mg ha −1 of yard waste compost were incorporated into the graded spoil (FGDC). In Treatment 3, 112 Mg ha −1 of limestone was incorporated into the graded spoil and was covered with 20 cm of graded borrowed topsoil (BTS). Six cores and six bulk soil samples were obtained from each treatment for the 0‐ to 10‐cm depth in summer 2002. From the 10‐ to 20‐cm depth, only bulk soil samples were obtained. Bulk and core soil samples were also collected from an unreclaimed spoil (SP) and a nearby unmined soil (UMS). Among the three reclamation treatments, BTS showed better soil quality with higher soil organic C (28.5 Mg ha −1 ), water‐stable aggregation (556 g kg −1 ), and mean weight diameter (3.2 mm) of aggregates than FGDC or FGD treatments. The FGDC had higher soil inorganic and organic C than FGD. However, saturated hydraulic conductivity ( K s ), cumulative infiltration ( I ), infiltration rates at 5 min ( i 5 ) and 2.5 h ( i c ), and soil pH were similar among three treatments. Among treatments and controls, soil bulk density (ρ b ) was lower for FGD, FGDC, and UMS than BTS and SP; and water‐stable aggregation and mean weight diameter of the aggregates was higher for UMS and BTS than FGDC, FGD, and SP for both depths. The I and i c were similar among UMS and treatments. Reclamation improved the soil quality with higher soil pH (≈7) and inorganic and soil organic C than in the SP. With respect to FGD, the soil organic C in FGDC increased at the rate of 0.64 Mg ha −1 yr −1 for the 0‐ to 10‐cm depth. Overall, BTS was the best reclamation treatment. However, if topsoil is unavailable or transport is expensive, FGDC can be used as an effective reclamation material.

The loss of nitrogen fertilizer into the atmosphere and waterways is of increasing concern for policy makers. This study conducts a cost-effective analysis (CEA) to determine the best strategies, and areas, to reduce nitrogen losses in South Dakota. This form of analysis is done by spatially comparing the amount of reductions per acre across the state, assuming alternative mitigation strategies and adoption rates. Using environmental factors, (Climate type, soil texture, soil organic carbon, soil drainage, soil pH and crop type), and management decisions (no till, conventional till, reduced till, crop rotations, and application timing), we assess the best areas and methods in South Dakota that can be targeted with management changes to gain the most cost effective continuous improvement in nitrogen losses. The Environmental Policy Integrated Climate (EPIC) model was used to simulate the homogeneous response units to changes in nitrogen management practices and assess nitrogen losses. Simetar was then used to derive certainty equivalence values for changes in nitrogen loss and producer returns from changes in nitrogen management.