Modelling of Soil Organic Carbon Dynamics in Kazakhstan

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Modeling of soil organic carbon and carbon balance under conservation agriculture in Kazakhstan

Traditional farming systems, involving intensive tillage, returning the low amounts of organic matter to field and frequently monoculture, lead to a decrease in soil organic carbon (SOC) and land degradation. In contrast, conservation agriculture (CA) has a large potential for carbon sequestration. However, the efficacy of no-till agriculture for increasing C in soils has been questioned in recent studies. These doubts stem from the facts that previous literature on soil C stocks has often discussed effects of tillage, rotations, and residue management separately. The objectives of this study are (1) to assess the potential of each CA component for soil C sequestration in Almaty state (Kazakhstan), proposing a methodology that could be extended to other conditions in Kazakhstan; and (2) to estimates CO2 balance and possibility to obtain carbon credits. Modeled results showed that no tillage with crop rotation and residue retained and/or cover crop increased SOC by about 300–1 000 kg-1 ha-1 yr-1 in the ploughing layer. It seems that the contribution of each CA element into SOC stock decreased in the following order: cover crops > residues > rotation. In particular, attention should be paid to cover crops, which seem to have significant role in C sequestration, but are not yet widely spread in practical farming in Kazakhstan. Conservation agricultural practices involving, in addition to no-tillage, crop rotation, residues retained and/or cover crops allowed achieving the objective of 4 per 1 000 initiatives. The initiative claims that an annual growth rate of 0.4 percent in the soil carbon stocks, or 4‰ per year, would halt the increase in the CO2 concentration in the atmosphere related to human activities. In addition, these CA practices had the negative total carbon balance indicating reduction of GHG emissions and indicating possibility to obtain carbon credits.202

Tillage system and cover crop effects on organic carbon and available nutrient contents in light chestnut soil

Optimal use of management systems including tillage and cover crops are recommended to improve available nutrient contents in soils and sustain agricultural production. The effects on organic carbon and available nutrient contents of three tillage methods (conventional tillage, minimum tillage and no-tillage) and different cover crops such as flaxseed oil, buckwheat, soybean, pea, corn, sorghum, spring oilseed rape and sugar beet were evaluated in a short-term experiment on a light chestnut soil in Kazakhstan. Organic carbon and available nutrient contents were measured in the autumn of 2021. The field measurements included the yield of cover crops and input of organic matter into soils with root and other residues of cover crops. In the laboratory, total organic carbon, labile organic carbon, easily hydrolyzable nitrogen (NH4-N), NO3-N, available P and exchangeable K were measured. The results showed that one season of cover crop growth was not enough to find detectable changes in soil organic matter and available nutrient status in light chestnut soils. On the other hand, even in a short-term field experiment period of 3 months, the most labile organic carbon in soil organic carbon was obtained in conventional tillage. Overall, the results show that at least in the short term and under lower drip irrigation rate in summer for the study area, reduced tillage methods (no-tillage and minimum tillage) is suitable in the study area for soybean, corn and sugar beet production after intensive tillage in the previous year

Screening of sweet and grain sorghum genotypes for green biomass production in different regions of Kazakhstan

As the impact of global climate change increases, the interaction of biotic and abiotic stresses increasingly threatens current agricultural practices. The most effective solution to the problem of climate change and a decrease in the amount of atmospheric precipitation is planting extremely drought-resistant and high-yielding crops. Sorghum can grow in harsh conditions such as salinity, drought and limited nutrients, also it is an important part of the diet in many countries. Sorghum can be introduced in many zones of Kazakhstan. Plant height and yield of green plant biomass of 16 sorghum samples in arid conditions were determined based on a set of agrobiological characteristics for field screening. The height of the studied samples of grain sorghum was 0.47 ±0.03 m, and the height of sweet sorghum was much longer, reaching up to 2.88 ±0.12 m. Also, there was a strong difference in green biomass in cultivated areas under different soil and climatic conditions, the green biomass of sweet sorghum was 3.0 Mg∙ha-1, and in grain sorghum, it reached up to 57.4 Mg∙ha-1. Based on the data of the field assessment for various soil and climatic conditions, the following samples were identified for introduction into production: samples of sweet sorghum for irrigated and rainfed lands of the Almaty Region and in the conditions of non-irrigation agriculture of the Aktobe Region - a promising line ICSV 93046. For non-irrigation agriculture of the Akmola Region, genotypes of sweet and grain sorghum are ‘Chaika’, ‘Kinelskoe 4’ and ‘Volzhskoe 44’