Wind erosion after steppe conversion in Kazakhstan

Semi-arid regions of Central Asia suffer from wind erosion due to expanding steppe conversion and unsustainable farming practices. Empirical data from field observations are needed to support the implementation of adapted management. In this study, a mobile wind tunnel was used for the first time in Kazakhstan to assess the soil's erodibility under real conditions. Field experiments were conducted on loamy sands with different initial conditions that are typical for the most erosive time of the year: a bare surface with a cloddy structure after recent steppe conversion, a weak crust on a plot with barley (Hordeum vulgare L.), and a plot with loose material in the rows of maize plants (Zea mays L.). Subsequently, different levels of mechanical stress (low, moderate, high) were considered to analyze the effect of disruptive forces soils experience during field cultivation (light cultivator, disc harrow, tractor tires) on possible soil losses. The results of wind tunnel experiments showed already great differences under initial conditions. The cloddy structure of the recent steppe conservation had the lowest susceptibility against wind erosion due to a good aggregation and a large roughness, resulting in soil loss of 12 g m−2. The plot grown with barley was less affected by wind erosion due to the weak crust, smaller distances between plants, and leaves close to the ground (soil loss of 34 g m−2). Maize was also the most problematic crop in the study area because wind can blow below the plant canopy without considerable resistance during the early growth stages. Additionally, existing deposits in the maize rows from previous erosion events led to the highest soil loss of 1609 g m−2. Mechanical stress by seedbed preparation generally increased the erodible fraction, resulting in higher soil losses (light cultivator: 198 ± 129 g m−2, disc harrow: 388 ± 258 g m−2). The most severe disruption of soil structure occurred on tractor tire tracks, causing a loss of 2767 ± 1810 g m−2. Consequently, the pulverizing effect of tractor tires on dry soil must be considered a serious emission source. Comparing the soil organic carbon content of topsoil and eroded material showed that organic carbon was enriched only in the aeolian sediments of the recently converted plot (+69%). We conclude that soils after steppe conversion need to be treated with particular care from the very beginning so that severe events from the past are not repeated

Soil protection technologies on medium saline irrigated lands

Factor that hinders cotton growth and development, deep rooting of plants, are soil salinization. Currently, intensive measures to combat soil salinization are a very important issue in the field of agriculture. Soils are one of the priceless natural resources that plays an important role in the agricultural production of food in the region. The role of soils is also important in water storing and filtering and increasing resistance to floods and droughts. Stabilization of the food security of the region and increase in crop yields, which mainly depends on the soil, therefore intensive tillage and increasing the content of essential nutrients in the soil is an urgent problem today. Currently, technologies and methods of sustainable and effective intensification of production systems in the direction of increasing production capacity have been developed and are gradually being implemented into production. One of such approaches is soil-protective and resource-saving agriculture. Therefore, in the direction of increasing the production capacity, on the experimental basis of the Agricultural Experimental Station of Cotton and Melon Growing, scientific research was conducted to reduce the content of harmful salts and increase the content of nutrients in the soil

Competition of Plants and Microorganisms for Added Nitrogen in Different Fertilizer Forms in a Semi-Arid Climate

In nitrogen (N) -limited agricultural systems, a high microbial immobilization of applied fertilizer-N can limit its availability to plants. However, there is scarce information on the effect of the form of fertilizer used on the plant–microorganism competition in clay-rich soils under a severe semi-arid climate. In a field study, we investigated the wheat–microorganism competition after the direct application of NH415NO3 closely to seeds in arable fields in North Kazakhstan, documenting the effect of the use of liquid versus granular fertilizer and mini-tillage versus no-tillage. Our results barely showed any fertilizer-N translocation in the soil. Plants outcompete microorganisms for fertilizer-N during the vegetation period. Microbial-to-plant 15N ratios revealed a predominant fertilizer-15N uptake by plants. The strong competition for N was mainly related to the placement of the fertilizer close to the seeds. Moreover, the long time interval between fertilization and sampling enhanced the competition for N, meaning that previously microbially immobilized N became available to plants through the death of microorganisms and their subsequent mineralization. The fertilizer distribution between microorganisms and plants did depend on the form of fertilizer used, owing to the good solubility of granular fertilizer. The smaller fertilizer-N uptake under the no-tilling condition was probably due to the more intense soil compaction, which caused a reduction in plant growth. The application of fertilizer close to the seeds and the small fertilizer translocation during the vegetation period ultimately resulted in a high level of plant N being derived from the fertilizer

Rational measures of agromelioration on grey soils

In the conditions of grey soils in the south of Kazakhstan, the soil is degraded due to irrational use of irrigated land and non-compliance with agro-reclamation works in its order, as well as excessive irrigation of medium-saline soil, it negatively affects crop yields. In addition, on medium-saline soils, winter plowing is carried out only to a shallow depth of 30-32 cm. Mainly on grey soils, with timely and intensive soil treatment, it is preferable, since the degree of bulk mass of gray soils in a stable indicator is 1.28-1.30 g/cm3. If agrotechnological measures are carried out incorrectly, i.e. it affects the increase in soil density and its salinization, which negatively affects the growth and productivity of agricultural crops. In conditions of decreasing soil fertility, scientists of our scientific institution have carried out experimental work to identify the effects of effective agro-reclamation measures on irrigated saline lands, based on the rational use of irrigated agriculture in the south of Kazakhstan. The first issue that hinders the development of agricultural crops and the regulation of the condition of the rooting layer of plants in the soil is soil salinization and measures to combat them, since this issue is very relevant in conditions of increasing irrigated agriculture intensity

Consequences of chemical pretreatments in particle size analysis for modelling wind erosion

The particle size distribution (PSD) of soil plays a vital role in wind erosion prediction. However, the impact of different pretreatments to remove binding agents for PSD and consequences for wind erosion modelling have not been tested. We collected 90 topsoil samples of Chernozems and Kastanozems from different test sites in Kazakhstan. Soil samples covered typical land-use types and farming methods with calcium carbonate contents reaching from 2.2 to 117.3 g kg−1 and soil organic carbon content from 11.2 to 48.7 g kg−1. Prior to particle size analysis by laser diffraction, samples were chemically pretreated separately and successively with 10% hydrochloric acid (HCl), to dissolve carbonates and 30% hydrogen peroxide (H2O2), to oxidise organic binding material. The HCl pretreatment resulted in incomplete dispersion or even aggregation due to calcium ions released by the dissolution of carbonates, while removing organic matter with H2O2 caused complete sample dispersion. The associated changes in PSD were overall minor, and only a few of our samples were assigned to a different texture class. Obtained PSD data was used to calculate texture-based properties, such as the geometric mean diameter (GMD), with a pedotransfer function. Calculated and measured input data were applied to the Single–event Wind Erosion Evaluation Program (SWEEP) to estimate potential soil losses. As a result, SWEEP's simulations showed substantial variations if the GMD is calculated based on PSD under the influence of different pretreatments. At the same time, there was no variation if the GMD was independently measured. We suggest that for standard particle size analysis of calcareous soils, pretreatment with HCl should be avoided because it might cause misleading results. Considering the variation induced by PSD analysis and resulting potential soil losses, pretreatments for laser diffraction analysis can be omitted for the investigated, silt-dominated Chernozems and Kastanozems if additional texture-based parameters are measured.Publikationsfonds ML

Land Use Influences Carbon Fluxes in Northern Kazakhstan

A mobile, closed-chamber system (CC) was used to measure carbon and water fluxes on four land-use types common in the Kazakh steppe ecoregion. Land uses represented crop (wheat or barley, WB), abandoned land (AL), crested wheatgrass (CW), and virgin land (VL). Measurements were conducted during the growing season of 2002 in northern Kazakhstan at three locations (blocks) 15-20 km apart. The CC allowed the measurement of the carbon flux components of net ecosystem exchange (NEE), ecosystem respiration (RE) and soil respiration (RS), together with evapotranspiration (ET). Nonlinear regression analyses were used to model gross primary production (GPP) and ET as a function of photosynthetically active radiation (Q); RE and RS were modeled based on air (Tair) and soil (Ts) temperature, respectively. GPP, RE, RS, and ET were estimated for the entire year with the use of continuous 20-min means of Q, Tair, and Ts. Annual NEE indicated that AL gained 536 g CO2 m-2, WB lost – 191 g CO2 m-2, CW was near equilibrium (–14g CO2 m-2), and VL exhibited considerable carbon accumulation (153g CO2 m-2). The lower GPP values of the land-use types dominated by native species (CW and VL) compared to WB and AL were compensated by positive NEE values that were maintained during a longer growing season. As expected, VL and CW allocated a larger proportion of their carbon assimilates belowground. Non-growing-season RE accounted for about 19% of annual RE in all land-use types. The results of this landscape-level study suggest that carbon lost by cultivation of VLs is partially being restored when fields are left uncultivated, and that VLs are net sinks of carbon. Estimations of carbon balances have important management implications, such as estimation of ecosystem productivity and carbon credit certification. The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Soil protection technologies on medium saline irrigated lands

Factor that hinders cotton growth and development, deep rooting of plants, are soil salinization. Currently, intensive measures to combat soil salinization are a very important issue in the field of agriculture. Soils are one of the priceless natural resources that plays an important role in the agricultural production of food in the region. The role of soils is also important in water storing and filtering and increasing resistance to floods and droughts. Stabilization of the food security of the region and increase in crop yields, which mainly depends on the soil, therefore intensive tillage and increasing the content of essential nutrients in the soil is an urgent problem today. Currently, technologies and methods of sustainable and effective intensification of production systems in the direction of increasing production capacity have been developed and are gradually being implemented into production. One of such approaches is soil-protective and resource-saving agriculture. Therefore, in the direction of increasing the production capacity, on the experimental basis of the Agricultural Experimental Station of Cotton and Melon Growing, scientific research was conducted to reduce the content of harmful salts and increase the content of nutrients in the soil

Potential erodibility of semi‐arid steppe soils derived from aggregate stability tests

Erosion is a severe threat to the sustainable use of agricultural soils. However, the structural resistance of soil against the disruptive forces steppe soils experience under field conditions has not been investigated. Therefore, 132 topsoils under grass‐ and cropland covering a large range of physico‐chemical soil properties (sand: 2–76%, silt: 18–80%, clay: 6–30%, organic carbon: 7.3–64.2 g kg−1, inorganic carbon: 0.0–8.5 g kg−1, pH: 4.8–9.5, electrical conductivity: 32–946 μS cm−1) from northern Kazakhstan were assessed for their potential erodibility using several tests. An adjusted drop‐shatter method (low energy input of 60 Joule on a 250‐cm3 soil block) was used to estimate the stability of dry soil against weak mechanical forces, such as saltating particles striking the surface causing wind erosion. Three wetting treatments with various conditions and energies (fast wetting, slow wetting, and wet shaking) were applied to simulate different disruptive effects of water. Results indicate that aggregate stability was higher for grassland than cropland soils and declined with decreasing soil organic carbon content. The results of the drop‐shatter test suggested that 29% of the soils under cropland were at risk of wind erosion, but only 6% were at high risk (i.e. erodible fraction >60%). In contrast, the fast wetting treatment revealed that 54% of the samples were prone to become “very unstable” and 44% “unstable” during heavy rain or snowmelt events. Even under conditions comparable to light rain events or raindrop impact, 53–59% of the samples were “unstable.” Overall, cropland soils under semi‐arid conditions seem much more susceptible to water than wind erosion. Considering future projections of increasing precipitation in Kazakhstan, we conclude that the risk of water erosion is potentially underestimated and needs to be taken into account when developing sustainable land use strategies. Highlights Organic matter is the important binding agent enhancing aggregation in steppe topsoils. Tillage always declines aggregate stability even without soil organic carbon changes. All croplands soil are prone to wind or water erosion independent of their soil properties. Despite the semi‐arid conditions, erosion risk by water seems higher than by wind.Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/50110000234

Rational measures of agromelioration on grey soils

In the conditions of grey soils in the south of Kazakhstan, the soil is degraded due to irrational use of irrigated land and non-compliance with agro-reclamation works in its order, as well as excessive irrigation of medium-saline soil, it negatively affects crop yields. In addition, on medium-saline soils, winter plowing is carried out only to a shallow depth of 30-32 cm. Mainly on grey soils, with timely and intensive soil treatment, it is preferable, since the degree of bulk mass of gray soils in a stable indicator is 1.28-1.30 g/cm3. If agrotechnological measures are carried out incorrectly, i.e. it affects the increase in soil density and its salinization, which negatively affects the growth and productivity of agricultural crops. In conditions of decreasing soil fertility, scientists of our scientific institution have carried out experimental work to identify the effects of effective agro-reclamation measures on irrigated saline lands, based on the rational use of irrigated agriculture in the south of Kazakhstan. The first issue that hinders the development of agricultural crops and the regulation of the condition of the rooting layer of plants in the soil is soil salinization and measures to combat them, since this issue is very relevant in conditions of increasing irrigated agriculture intensity