Tree regeneration characteristics in limestone forests of the Cat Ba National Park, Vietnam

Background The ability of overstory tree species to regenerate successfully is important for the preservation of tree species diversity and its associated flora and fauna. This study investigated forest regeneration dynamics in the Cat Ba National Park, a biodiversity hotspot in Vietnam. Data was collected from 90 sample plots (500 m2) and 450 sub-sample plots (25 m2) in regional limestone forests. We evaluated the regeneration status of tree species by developing five ratios relating overstory and regeneration richness and diversity. By examining the effect of environmental factors on these ratios, we aimed to identify the main drivers for maintaining tree species diversity or for potential diversity gaps between the regeneration and the overstory layer. Our results can help to increase the understanding of regeneration patterns in tropical forests of Southeast Asia and to develop successful conservation strategies. Results We found 97 tree species in the regeneration layer compared to 136 species in the overstory layer. The average regeneration density was 3764 ± 1601 per ha. Around 70% of the overstory tree species generated offspring. According to the International Union for Conservation of Nature’s Red List, only 36% of threatened tree species were found in the regeneration layer. A principal component analysis provided evidence that the regeneration of tree species was slightly negatively correlated to terrain factors (percentage of rock surface, slope) and soil properties (cation exchange capacity, pH, humus content, soil moisture, soil depth). Contrary to our expectations, traces of human impact and the prevailing light conditions (total site factor, gap fraction, openness, indirect site factor, direct site factor) had no influence on regeneration density and composition, probably due to the small gradient in light availability. Conclusion We conclude that the tree species richness in Cat Ba National Park appears to be declining at present. We suggest similar investigations in other biodiversity hotspots to learn whether the observed trend is a global phenomenon. In any case, a conservation strategy for the threatened tree species in the Cat Ba National Park needs to be developed if tree species diversity is to be maintained.

Agrotechnological passport of the potato variety Azart

Цель исследований: изучить реакцию нового среднераннего сорта картофеля Азарт селекции ФГБНУ «ФИЦ картофеля имени А.Г. Лорха» на густоту, сроки посадки и способы внесения минеральных удобрений, по комплексу хозяйственно ценных признаков (морфологические и биологические особенности, потребительские и столовые качества клубней, урожайность, показатели качества клубней, устойчивость к болезням, лежкость при хранении). Опыты проводили на экспериментальной базе «Коренево» ФГБНУ «ФИЦ картофеля имени А.Г. Лорха» (Московская область) в 2018–2020 годах на дерново-подзолистой супесчаной почве с низким содержанием гумуса (1,8–1,9%), высоким – подвижного фосфора (269–278 мг/кг почвы) и ниже среднего – обменного калия (128–130 мг/кг почвы). Минеральные удобрения (азофоска с добавлением калимагнезии) вносили локально двумя лентами при нарезке гребней культиватором КРН-4,2 с туковысевающими аппаратами в середине апреля. Изучали три приема внесения: 1. Единовременное N90P90K135(контроль); 2. Дробно-локальное (стартовое N60P60K90+ подкормка N30P30K45) через 7–10 дней после всходов; 3. Дробное (стартовое N30P30K45 + подкормка N30P30K45) через 7–10 дней после всходов + подкормка N30P30K45 в фазе бутонизации. Посадку картофеля проводили в два срока: ранний (третья декада апреля при температуре почвы не ниже 5–7 °C) и базовый (контроль) – через 7–10 дней после первого срока. Клубни массой 50–80 г высаживали клоновой сажалкой СН-4Б-К на глубину 8–10 см. Исследовали три густоты посадки: 44 (контроль), 50 и 56 тыс. клубней/га по схеме 75×30, 75×27, 75×24 см. Определен наиболее эффективный агрокомплекс приемов, включающий раннюю посадку (третья декада апреля при температуре почвы не ниже 5–7 °C) с густотой 44 тыс. клубней/га на фоне дробно-локального внесения удобрений (стартовое N60P60K90при нарезке гребней + подкормка N30P30K45) при междурядной обработке через 7–10 дней после всходов. В условиях дерново-подзолистой супесчаной почвы Центрального региона Нечерноземной зоны сорт дает прибавку урожая в размере 3,9 т/га, или 10,3%. При этом условный доход составил 39,0 тыс. р/га. The purpose of the research: to study the reaction of a new medium-early potato variety Azart selection of the Russian Potato Research Centre on the density, planting dates and methods of applying mineral fertilizers, according to a complex of economically valuable characteristics (morphological and biological features, consumer and table qualities of tubers, yield, quality indicators of tubers, resistance to diseases, storage shelf life). The experiments were carried out at the experimental base Korenevo Russian Potato Research Centre (Moscow region) in 2018–2020 on sod-podzolic sandy loam soil with low humus content (1.8–1.9%), high – mobile phosphorus (269–278 mg/kg of soil) and below average – exchangeable potassium (128–130 mg/kg of soil). Mineral fertilizers (azofoska with the addition of kalimagnesia) were applied locally with two ribbons when cutting the ridges with a KRN-4,2 cultivator with tow-raising devices in mid-April. We studied three methods of making: 1. One-time N90P90K135 (control); 2. Fractional-local (starting N60P60K90 + top dressing N30P30K45) 7–10 days after germination; 3. Fractional (starting N30P30K45+ top dressing N30P30K45) 7–10 days after germination + top dressing N30P30K45 in the budding phase. Potato planting was carried out in two terms: early (the third decade of April at a soil temperature of at least 5–7 °C) and basic (control) – 7–10 days after the first term. Tubers weighing 50–80 g were planted with a clone planter CH-4B-K to a depth of 8–10 cm. Three planting densities were studied: 44 (control), 50 and 56 thousand tubers/ha according to the scheme 75×30, 75×27, 75×24 cm. The most effective agrocomplex of techniques has been determined, including early planting (the third decade of April at a soil temperature of at least 5–7 °C) with a density of 44 thousand tubers/ha against the background of fractional-local fertilization (starting N60P60K90when cutting ridges + top dressing N30P30K45) with row-to-row processing 7–10 days after germination. In the conditions of sod-podzolic sandy loam soil of the Central region of the Non-Chernozem zone, the variety gives an increase in yield of 3.9 t/ha or 10.3%. At the same time, the conditional income amounted to 39.0 thousand rubles/ha.

Tin and Antimony as Soil Pollutants along Railway Lines—A Case Study from North-Western Croatia

The aim of this study was to determine the extent and patterns of antimony and tin contamination in soils along railway lines, as there are very few data in the literature on this subject. The study was conducted in north-western Croatia. Total and bioavailable concentrations of Sn and Sb were detected using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The following results were obtained: total concentrations of Sb ranged from 0.98 to 52.0 mg/kg and of Sn from 3.04 mg/kg to 97.6 mg/kg. The soil samples showed pronounced Sb and Sn enrichment, up to 87 and 33 times the median value for European soils, respectively. In contrast to the total concentrations, the bioavailable concentrations showed relatively low values. For Sn, the percentage of total content ranged from 0.001 to 0.021%, while for Sb it ranged from 0.001 to 0.136%. Statistical data analysis suggests that the distribution of Sb and Sn in soils near railway lines is influenced by the functional use of the site, distance from the tracks, topography, age of the railway line, and also by soil properties such as soil texture, humus content, and soil pH. This study demonstrates that rail transport is a source of soil pollution with Sn and Sb. The origin of Sb and Sn enrichment is abrasion by brakes, rails, wheels, freight losses, exhaust gasses, etc. Both elements in soils along railway lines pose an environmental risk to humans, agricultural production, and wildlife, and therefore further detailed studies are required.

NUTRITIONAL VALUE OF GRAIN VARIETIES OF SPRING BARLEY OF TATAR RESEARCH INSTITUTE SELECTION

Four varieties and 3 promising lines of spring barley breeding by Tatar Research Institute of Agriculture were studied for grain nutrition to identify the most promising ones. The work was conducted in 2015-2017 in Predkamye Republic of Tatarstan. Grey forest soil, humus content 3.35-3.52 % (GOST 26213-91), alkaline-hydrolyzable nitrogen 85.0...94.0 mg/kg (by A.H. Kornfield), mobile phosphorus 251...287 and exchangeable potassium 149...167 mg/kg (by Kirsanov; GOST 26207-91). The predecessor is winter rye, the repetition is fourfold, the standard grade is Raushan. It was found that line k-295-12, on average over 3 years, significantly exceeded the standard by 27.77 g in crude protein content; by 20.0 g in digestible protein content and by 7.35 g in digestible protein content per feeding unit. The variability of sugar content in varieties was 30.67 ... 47.0 g, significantly exceeded the standard by 13.33 g variety Tevkech (47.0 g) and by 13.0 g line k-23-13 (46.67 g). The fat content was formed in the standard 19.03 g, varieties Kamashevsky, Endan and lines k-23-23, k-561-13 and k-295-12 exceeded it by 7.47; 5.77; 11.47; 9.84 and 5.67 g, respectively. The exchange energy content in grain ranged from 14.42 MJ of the variety Raushan, to 14.72 MJ of the line k-295-12, with no significant differences between genotypes. In the dry year of 2015, the crude and digestible protein content was 148.0...165.0 and 110.74...118.8 g, respectively, and in 2016 it was 129.00...164.4 and 92.88...118.37 g, respectively. In favorable 2017, the content of crude and digestible protein were lower, the varieties Raushan and Tevkech were characterized by the greatest decrease in crude and digestible protein (65.7 and 67.4 % to the level of 2015). On average over 3 years, the best line was k-295-12 for the set of indicators of grain nutrition

Influence of tillage methods on the yield of winter rye variety Sudarushka

The results of studying the elements of the technology of cultivation of a new variety of winter rye Sudarushka are presented. The research took place in 2019, 2020 in the sub-taiga zone of the Tomsk region. The impact of soil cultivation methods as well as the impact of humic fertiliser from peat Gumostim on the yield of winter rye Sudarushka is evaluated. The soils of the experimental plot are acidic (pH 4.3) soddy-podzolic loamy sandy loam. The arable horizon has a low humus content (1.5%), a low (0.2 mg/100g) content of nitrate nitrogen, a medium content of mobile phosphorus (19.2) and exchangeable potassium (7.1) and a high (11.0 mg/100g) content of mobile aluminium. The scheme of the experiment included four variants of cultivation: ploughing of fallow lands with PlN-4-35 + cultivation KPN-4,2, sowing without packing and with packing; disking with BDMK-2,8 + cultivation KPN-4,2, sowing without packing and with packing. Treatment with humic fertilizer from peat Gumostim at a concentration of 0.001% was carried out during the growing season in the beginning phase of the leaf-tube formation. The average yield of winter rye in the variety Sudarushka during the years of research was 4.66 t/ha in the variant with disking, subsequent cultivation before sowing and further sowing with packing, which is 0.34 t/ha higher than with the traditional method of soil cultivation. The application of humic fertilizer from peat Gumostim on cold sod-podzolic soils enabled the average yield of winter rye to be 4.31 t/ha y, which is 0.39 t/ha higher than without the fertilizer.

Еdapho-climatic characteristics of Рrecarpathian biotopes with the participation of price populations of species of the genus Рolygonatum Мill.

Grouping of research sites according to the set of analyzed edapho-climatic parameters by the method of cluster analysis showed that the dominant factor in the formation of abiotic conditions is the type of habitat. Therefore, characterized the population and ecological characteristics of species of the genus Polygonatum Mill. in the Precarpathians by analyzing the key edapho-climatic factors of the studied habitats, namely the humus content, acidity, moisture content, the sum of active temperatures, light levels and N, P, K.

The effect of moisture supply conditions on productivity of winter bread wheat, sown after various forecrops in the southern part of the Rostov region

Weather and climatic conditions determine moisture supply, which is the main factor affecting winter wheat productivity in the area of unstable moisture. The current study was carried out on the experimental plot of the laboratory for cultivation technology of grain crops of the FSBSI Agricultural Research Center “Donskoy” in 2010–2020. The soil of the experimental plot was ordinary calcareous heavy loamy blackearth (chernozem). The humus horizon was powerful up to 140 cm. The humus content was 3.9%. The purpose of the study was to establish the moisture supply of winter bread wheat when cultivated according to various forecrops. There has been found that the autumn periods in the most years of study were arid with 37% of precipitation. Winter wheat plants from September to June were provided with 70% of precipitation, with a 1022.55 of air humidity deficit and 664.7 mm of water demand. There was found that, on average over the years of study, 88% of moisture supply promoted yielding of 7.03 t/ha of winter wheat sown in weedfree fallow. In order to yield a ton of grain there was required 591.7 m3 of total moisture. The share of precipitation in this moisture consumption was 84%, and the share of soil moisture was 16%. When sown after sunflower, moisture provision was 77%, and winter wheat yield was 5.32 t/ha. In order to yield a ton of grain there was required 657.3 m3 of total moisture, which was on 65.6 m3 more than in the variant with a weedfree fallow. The share of precipitation in this moisture consumption was 96%, and the share of soil moisture was 4%.

Agroecological assessment of saline soils of Iran

For the studied saline soils, the expediency of assessing the content of mobile ion compounds by chemical autography based on electrolysis and ionite membranes, vertical electrical sensing is shown. However, the electrical conductivity of soils depended on humidity, temperature, humus content, granulometric composition, soil density, and fertilizer application. The change in the nature and degree of soil salinization over time and in space was determined not only by the microrelief of the surface, groundwater and the change in the depth of the umbrellas in density, but also by the patterns of solubility of salts from humidity, temperature, pCO2, complex formation. For relative optimization of the situation, it is recommended to apply mineral fertilizers, stimulants, organic fertilizers, and create a large-porous layer at a depth of 40-70 cm, reducing the upward current from the lower layers of the soil to the Ap. Keywords: SOIL, SALINIZATION, WAYS OF OPTIMIZATION

Organic substances replenishment and high humus content of soil in the apple orchads under different fertilization

The balance of humus in a meter layer of dark gray, podzolized soil and podzolized chernozem of the experimental apple orchads and the study of their long-term fertilization was investigated (from the planting to 50-year old trees) with the use of organic (40 t/ha of cattle manure) and mineral fertilizers (N120P120K120), which were applied once in two years in autumn under the plowing in the row spacings at a depth of 18 20 cm. In the 20-year period (from 30- to 50-year-old experimental gardens) in a meter layer of dark gray podzolized soil on the non-fertilized control plots the amount of humus increased by 27 t/ha, and on the plots fertilized with manure – by 7 t/ha more and on the plots with mineral fertilizers – by 6 t/ha less and in podzolized chernozem – 37 t/ha and 3 t/ha more and 10 t/ha less respectively. Such changes in humus storage were caused by different replenishment of organic substances, and, to a greater extent, an increase in the biological activity of the fertilized soil, in particular the intensity of mineralization processes of organic matter, and in particular the humus compounds. Also, the replanishment of such soils in the gardens by the organic mass of fallen leaves and thin (d≤1mm) small roots, which systematically grows and dies, providing root nutrition of fruit plants, was investigated. These sources supplemented with organic substances the layer of soil of 0 20 cm – with all the mass of leaves and 38,5 43,3% of the total roots, and the increase in humus content was in all roots of the layer of 0 60 cm: in non-fertilized areas of 11 t/ha in dark gray soil and 18 tons per hectare in chernozem, under organic fertilizers, by 14 and 19 t/ha, and under mineral fertilizers – by 3 and 9 t/ha respectively. The greatest quantity of humus was added in the layer 60 100 cm: 16 and 19 t/ha, 20 and 21 t/ha and 18 t/ha. Such results were conditioned by the intensification of biological activity, in particular mineralization processes, in the upper layers of fertilized soils at higher humus content, as well as the migration of soluble humus substances deep into the meter profile.

Influence of Soil Genesis Factors on Gurghiu Mountain Forest Soils’ Physical and Chemical Properties

This research aimed to determine the values of chemical properties and the relationships between the main pedoecological factors that characterize the soils in the Gurghiu Mountains. The mapping surveys were carried out on an area of 4,647.36 ha located in the mixed mountain forest sites (FM2) (1,000–1,400 m altitude). The area was stratified into homogeneous site units in terms of climate, hydricity, and trophicity. At the level of the elementary site units, 35 main soil profiles and 46 control profiles were placed. The number of profiles was determined statistically to ensure an error of no more than 10%. Soil samples collected from the main profiles were analyzed in the laboratory. Soil’s properties values decreased on the soil’s profile (humus content from 15 to 2%, nitrogen from 1.1 to 0.5%, sum of exchangeable hydrogen from 20 to 9 me/100 g soil, and total cationic exchange capacity from 38 to 20 me/100 g soil), except the pH and the base saturation degree (the pH increased on profile from 4.5 to 6, and the base saturation degree from 40 to 70%). The soil properties, except for moisture, were significantly affected by altitude, and decreased when the altitude increased. Soil trophicity can be characterized by a soil index, the values of which were between 17 and 42 for the analyzed soils. These values indicated soil-specific trophicity levels from oligotrophic to eutrophic.