Dryland irrigation increases accumulation rates of pedogenic carbonate and releases soil abiotic CO2

Agricultural fields in drylands are challenged globally by limited freshwater resources for irrigation and also by elevated soil salinity and sodicity. It is well known that pedogenic carbonate is less soluble than evaporate salts and commonly forms in natural drylands. However, few studies have evaluated how irrigation loads dissolved calcium and bicarbonate to agricultural fields, accelerating formation rates of secondary calcite and simultaneously releasing abiotic CO2 to the atmosphere. This study reports one of the first geochemical and isotopic studies of such “anthropogenic” pedogenic carbonates and CO2 from irrigated drylands of southwestern United States. A pecan orchard and an alfalfa field, where flood-irrigation using the Rio Grande river is a common practice, were compared to a nearby natural dryland site. Strontium and carbon isotope ratios show that bulk pedogenic carbonates in irrigated soils at the pecan orchard primarily formed due to flood-irrigation, and that approximately 20–50% of soil CO2 in these irrigated soils is calcite-derived abiotic CO2 instead of soil-respired or atmospheric origins. Multiple variables that control the salt buildup in this region are identified and impact the crop production and soil sustainability regionally and globally. Irrigation intensity and water chemistry (irrigation water quantity and quality) dictate salt loading, and soil texture governs water infiltration and salt leaching. In the study area, agricultural soils have accumulated up to 10 wt% of calcite after just about 100 years of cultivation. These rates will likely increase in the future due to the combined effects of climate variability (reduced rainfall and more intense evaporation), use of more brackish groundwater for irrigation, and reduced porosity in soils. The enhanced accumulation rates of pedogenic carbonate are accompanied by release of large amounts of abiotic CO2 from irrigated drylands to atmosphere. Extensive field studies and modelling approaches are needed to further quantify these effluxes at local, regional and global scales.

The Effectiveness of the Application of Comprehensive Measures to Combat Erosion Using Irrigation in a Market Economy in Azerbaijan: on the Example of the Kur-Araks Plain

Studies in the article have shown that productivity increases with improved structure. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates of 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover crops this indicator is 35.0; Increased to 24.7 and 27.0. In addition, it revealed the accumulation of more organic and mineral substances under alfalfa cultivation. They proved this by the analysis of soil samples taken from the one-year and two-year plots. It was found that 1.66% humus and 0.112% total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil in the biennial clover field was 1.70% and the total nitrogen content was 0.150%. It should be noted. that the development of irrigation erosion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In heavy rains, the depth of the furrow under alfalfa is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm

First Report of Alfalfa Root Rot Caused by Plectosphaerella cucumerina in Inner Mongolia Autonomous Region of China

Alfalfa (Medicago sativa L.) is an important forage crop with high nutrition for animal feed. In May 2016, a disease showing brown root rot was observed on alfalfa collected from several farms in Tongliao City (44°17′ N; 121°29′ E), Inner Mongolia Autonomous Region of China. The incidence of brown root rot was approximately 50 to 70% in the 2-year-old alfalfa field. Infected alfalfa exhibited varying degrees of decay in the tap root. Symptomatic roots were cut into 0.5-cm pieces, surface disinfected with 70% ethanol for 5 s and 0.1% HgCl2 for 35 s, then rinsed with sterilize distilled water three times, and placed onto potato dextrose agar (PDA) at 26°C in the dark. After 5 days, hyphal tips of the growing colonies were transferred onto PDA plates for purification. Forty-four isolates belonging to five fungal species were obtained from 20 diseased root samples. Six of the isolates resembled the genus Plectosphaerella. Colonies of these isolates were white to cream in color with sparse aerial mycelium, and then gradually became salmon pink with slimy or moist mycelium. The hyphae were transparent and branched. Colonies produced numerous hyphal coils with conidiophores. Conidiogenous cells and conidia were both hyaline, solitary, and smooth. Conidia were 4 to 8.5 ×1.2 to 4.8 µm (n= 100), 0 to 1 septum, elliptical and ovoid, and aggregating to form a head (Palm et al. 1995). According to these morphological characteristics, the fungus was identified as P. cucumerina (Lindf.) (Carlucci et al. 2012). To confirm the identification, the genomic DNA of two representative isolates was extracted and their internal transcribed spacer (ITS) region was amplified and sequenced with the primer pair ITS1/ITS4 (White et al. 1990). The ITS sequences of the two isolates were deposited in GenBank (acc. nos. MN915126 and MN915127). The two ITS sequences showed 99 to 100% identical to known P. cucumerina strains CBS 131739 (acc. no. KY662258.1) (Su et al. 2017) and MP313 (acc. no. KC756835.1) from alfalfa in China (Wen et al. 2015). To test for pathogenicity, a set of 15 alfalfa seedlings (cv. Aohan) were root-dipped in the conidial suspension of one of the isolates (1×105 conidia /ml) prepared from 7-day-old cultures on PDA. Inoculated seedlings were transplanted in three pots (10×15 cm) with sterilized nursery soil. Another set of five alfalfa seedlings inoculated with sterile water only served as the controls. Treated alfalfa seedlings were maintained in a greenhouse at 25°C to 28°C under a 12-h photoperiod. After 25 days, the roots of all inoculated plants showed brown lesions. P. cucumerina was reisolated from symptomatic tissue. No symptoms were observed on the control plants. P. cucumerina was previously reported on alfalfa in the fields of Huanxi Country (36°20′ N; 107°21′), Gansu Province, China (Wen et al. 2015). To our knowledge, this is the first report of P. cucumerina causing root rot of alfalfa in Inner Mongolia Autonomous Region, China. This disease may cause serious economic losses in the region. It is needed to develop effective management strategies for control of this disease.

The Effectiveness of The Application of Comprehensive Measures To Combat Erosion Using Irrigation In A Market Economy In Azerbaijan (On The Example Of The Kur-Araks Plain)

Studies in the article have shown that productivity increases with improved structure. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates of 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover crops this indicator is 35.0; Increased to 24.7 and 27.0. In addition, it revealed the accumulation of more organic and mineral substances under alfalfa cultivation. They proved this by the analysis of soil samples taken from the one year and two-year plots. It was found that 1.66% humus and 0.112% total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil in the biennial clover field was 1.70% and the total nitrogen content was 0.150%. It should be noted. That the development of irrigation erosion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In heavy rains, the depth of the furrow under alfalfa is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm.

Efficiency of Application of Integrated Measures To Combat Erosion With The Use of Irrigation Systems In Azerbaijan

Studies in the article have shown that productivity increases with improved structure. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates of 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover crops this indicator is 35.0; Increased to 24.7 and 27.0. In addition, it revealed the accumulation of more organic and mineral substances under alfalfa cultivation. They proved this by the analysis of soil samples taken from the one year and two-year plots. It was found that 1.66% humus and 0.112% total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil in the biennial clover field was 1.70% and the total nitrogen content was 0.150%. It should be noted. that the development of irrigation erosion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In heavy rains, the depth of the furrow under alfalfa is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm.

EFFECTIVENESS OF THE APPLICATION OF COMPLEX MEASURES TO COMBAT IRRIGATION EROSION IN AZERBAIJAN IN A MARKET ECONOMY (ON THE EXAMPLE OF THE KUR-ARAZ LOW LAND)

The research in the article proves that the improvement of the structure increases the productivity. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover plantations this indicator is 35.0; Increased to 24.7 and 27.0. In addition, the accumulation of more organic and mineral substances under alfalfa cultivation was revealed. This was confirmed by the analysis of soil samples taken from the one-year and two-year plots. It was found that 1.66% of humus and 0.112% of total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil of the biennial alfalfa was 1.70% and the total nitrogen content was 0.150%. that the development of irrigation ero-sion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In intensive rains, the depth of the furrow under the clover is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm

THE EFFECTIVENESS OF THE APPLICATION OF COMPREHENSIVE MEASURES TO COMBAT EROSION USING IRRIGATION IN A MARKET ECONOMY IN AZERBAIJAN (ON THE EXAMPLE OF THE KUR-ARAKS PLAIN)

Studies in the article have shown that productivity increases with improved structure. This is explained by the fact that in soils with 0.25 mm diameter water-resistant aggregates of 14%, grain yield is 22.2 cents / ha, while water-resistant aggregates are 8%. In soils, this figure decreased to 18.4 cents / ha (3.8 cents / ha). It is also known that alfalfa plays a key role in improving the water-physical properties of the soil, as well as its agrochemical composition. The author's research shows that the amount of water-resistant aggregates under the clover is much higher than in the cotton fields. This can be clearly seen from the following comparison. Thus, the amount of water-resistant aggregates in 0-10 cm of soil in the cotton field is 4.0-18.5; While 0.5 cm is 6.5-11.2 and 20-30 cm is 4.5-18.2, in clover crops this indicator is 35.0; Increased to 24.7 and 27.0. In addition, it revealed the accumulation of more organic and mineral substances under alfalfa cultivation. They proved this by the analysis of soil samples taken from the one-year and two-year plots. It was found that 1.66% humus and 0.112% total nitrogen were accumulated in the topsoil of the annual alfalfa field, while the amount of humus accumulated in the topsoil in the biennial clover field was 1.70% and the total nitrogen content was 0.150%. It should be noted. that the development of irrigation erosion in irrigated arable lands depends on the fact that the surface of the area is covered with a large cover. This was clearly shown by the observations. It was found that both relatively weak (0.4 mm / min) and very (1.4 mm / min) heavy rains protect clover soil from further washing. Thus, 0.4 mm / min. In heavy rains, the depth of the furrow under alfalfa is 14.4 mm, 31 mm at 1.4 mm / min, 50.9 and 64.2 mm between rows of cotton, respectively, and 78.6 and 113 mm along the row. 6 mm

Soil N2O emissions after perennial legume termination in an alfalfa-wheat crop rotation system under Mediterranean conditions

Agricultural activities are potential sources of greenhouse gas (GHG) emissions, and nitrous oxide (N2O) is one of the most important non-carbon-dioxide GHGs. Perennial legumes such as alfalfa (Medicago sativa L.) have potential roles for reduction of soil GHG emissions as part of crop rotation systems. However, the implications of perennial legume termination by tillage and subsequent soil incorporation of the residues for reduced GHG emissions have been poorly examined in Mediterranean environments. With the aim to assess the magnitude of soil N2O emissions (important for the definition of mitigation strategies) after perennial legume termination in alfalfa-wheat crop rotation systems in a Mediterranean environment, we defined the hypothesis that alfalfa termination by tillage with incorporation of the crop residues will increase soil N2O emissions during the subsequent wheat season. To test this hypothesis, closed static chambers were used in a field–plot experiment, using a complete randomised block design with three replicates. Soil N2O emissions were monitored across 33 sampling dates from October 2017 to July 2018, as a comparison between an original 6-year-old alfalfa field (‘continuous alfalfa’) and alfalfa termination followed by wheat (‘alfalfa+ wheat’). The soil N2O emission fluxes varied markedly across the treatments and throughout the monitoring period (from – 0.02±0.01 to 0.53±0.14 g N-N2O ha–1 h–1, and from 0.02±0.07 to 0.37±0.11 g N-N2O ha–1 h–1 for continuous alfalfa and alfalfa+wheat, respectively), generally following the changes in soil temperature. Several soil N2O emission peaks were recorded for both treatments, which mainly coincided with rainfall and with increased soil water content. In the 2 months following alfalfa termination, alfalfa+wheat showed higher cumulative weekly soil N2O emissions compared to continuous alfalfa. Following alfalfa termination for alfalfa+wheat, the increased cumulative weekly soil N2O emissions appeared to be due to asynchrony between nitrogen (N) released into the soil from mineralisation of the alfalfa residues and N uptake by the wheat. Despite these initial high soil N2O emissions for alfalfa+wheat, the seasonal cumulative soil N2O emissions were not significantly different (0.77±0.09 vs 0.85±0.18 kg N-N2O ha–1 for continuous alfalfa and alfalfa+wheat, respectively). These data suggest that legume perennial crop termination in alfalfa–wheat rotation systems does not lead to significant loss of N2O from the soil. The alfalfa termination by tillage performed in autumn might, on the one hand, have slowed the mineralisation process, and might, on the other hand, have synchronised the N release by the mineralised crop residues, with the N uptake by the wheat reducing the soil N2O emissions.