Low Soil Moisture Research Articles

Tillage and nitrogen managements increased wheat yield through promoting vigor growth and production of tillers

AbstractAdopting suitable tillage and fertilization technologies for wheat (Triticum aestivum L.) can address poor soil conditions and high residual nitrogen following rice (Oryza sativa L.) harvest to improve the sustainability of rice–wheat rotation systems. A field experiment was conducted in 2016–2018 to investigate the influence of tillage methods and nitrogen rates on wheat seedling growth (at the beginning of over‐wintering stage), tillering characteristics, and grain yield. The tillage methods included no‐tillage (NT), rotary tillage twice (RR), and plow tillage followed by rotary tillage (PR). The nitrogen rates were 270 (N270), 240 (N240), and 210 kg ha−1 (N210). In 2016–2017 (higher soil moisture during tillage), NT improved early growth (i.e., leaf area and biomass per stem), single spike yield, and grain yield compared with PR and RR. In 2017–2018 (lower soil moisture during tillage), PR and RR resulted in stronger seedlings (greater tiller number and leaf area and biomass per stem), more fertile tillers, and higher grain yield than NT. In both years, grain yield under RR was between that of PR and NT. With reduced nitrogen application, seedling growth, tiller number, single spike yield, and grain yield showed a declining tendency. We found that more tillers at seedling growth stage (the five‐leaf stage in both years) could boost fertile tiller number, and at this time greater leaf area and biomass per stem were correlated with higher single spike yield. This study demonstrates that suitable tillage and fertilizer applications can facilitate yield formation through improved number and vigor of the early‐produced tillers.

Study of soil physical properties in UIN Sunan Gunung Djati campus area using geoelectrical resistivity method

Study of Soil physical properties are important characteristics of the soil. The description of soil physical properties is very important to investigation the function of the soil as a plant growth medium. The aim of this study was to determine the physical properties of the soil based on geoelectric resistivity data. The study was conducted in UIN Sunan Gunung Djati campus area. The method used in this study was geoelectrical resistivity of wenner configuration method. The results showed the value of resistivity, porosity and soil fraction. Range value of Soil resistivity was 50-800 Om. Soil porosity was 5-50%. The soil fraction component consists of coarse sand, fine sand and clay. Soil resistivity was inversely proportional to soil porosity. The high soil resistivity is likely due to the low soil moisture, causing generally campus area still open. Based on the soil fraction component, soil texture in the campus area tends to be Loam Sandy. It is good for aeration and water holding. This condition is very good for plant growth.

Phenetic analysis and habitat preferences of wild orchids in Gunung Gajah, Purworejo, Indonesia

Abstract. Purba THP, Chasani AR. 2021. Phenetic analysis and habitat preferences of wild orchids in Gunung Gajah Purworejo. Biodiversitas 22: 1371-1377. Orchid (Orchidaceae) is one of the largest flowering plant families comprising more than 25.000 species. Knowledge of wild orchid diversity and their habitat preferences is useful for its conservation efforts. Research of wild orchid diversity in Indonesia has been done before, however, there is still few information about phenetic analysis and habitat preferences of wild orchids in Indonesia particularly in Gunung Gajah, Purworejo, Indonesia. Therefore, our research aimed to study species diversity and phenetic relationship of wild orchids and their habitat preferences in Gunung Gajah, Purworejo. Exploration was done using purposive sampling method. Phenetic analysis was carried out using MVSP 3.1, implemented by clustering method to understand phenetic relationships and ordination by PCA method to reveal morpho-anatomical characters which determine the clustering pattern. Thirteen orchid species of subfamily Vanilloideae, Orchidoideae, and Epidendroideae were found. Two clusters were formed on dendrogram and each of them was separated into two sub-clusters. PCA analysis based on stem, leaf, and flower characters showed different clusters compared to dendrogram. Habitat preferences of wild orchids in Gunung Gajah are alkaline soil, low soil moisture, air temperature 24-29°C, and low to high light intensity. Epiphytic orchids preferences on their host tree are dominated by median and upper part of main stem.

The relative contribution of intraspecific variation and species turnover to the community-level foliar stoichiometric characteristics in different soil moisture and salinity habitats.

BackgroundTrait-based approaches have been used to demonstrate the responses of plant functional traits to environmental change may manifest both among- and/or within-species. However, how community-level foliar stoichiometric characteristic variations respond to aridity and salinity is still not well-known.MethodsWe calculated community weighted means (CWMs) and non-weighted means (CMs) of foliar C, N, and P concentrations (and their ratios) in a dryland plant community respond to high (HSW) and low soil moisture and salinity (LSW). Based on a sum of squares decomposition method, we determined the relative contributions of intraspecific variation and species turnover in both HSW and LSW habitats.ResultsThe CWMs of foliar C, C:N and C:P, and CM of N in the HSW habitat were significantly greater than those in the LSW habitat. The trait variations in two habitats were mainly driven by intraspecific variation, and its contribution to trait variation mostly declined with the decrease of soil moisture and salinity. The CWMs of foliar C-related stoichiometric characteristics were mainly dominated by species turnover in both habitats. Moreover, the contribution of species turnover to C and C:P variations showed an increasing trend in the LSW habitat. For CWMs, negative covariations between intraspecific variation and turnover occurred in HSW and positive covariations (except N:P) occurred in LSW; however, CMs were generally positively correlated in both habitats.ConclusionsThe intraspecific variation declined as drought stress intensified, which indicates that the adaptability of desert plants declined when the stress changed from salinity to aridity. The total variation of C-related traits in both habitats were mainly dominated by species turnover. These findings highlight the importance of intraspecific variation in driving desert plant response of community functional composition to salt stress, and the joint role of intraspecific variation and species turnover in resisting drought stress.

Physiological Conditions and dsRNA Application Approaches for Exogenously induced RNA Interference in Arabidopsis thaliana.

Recent studies have revealed that foliar application of double-stranded RNAs (dsRNAs) or small-interfering RNAs (siRNAs) encoding specific genes of plant pathogens triggered RNA interference (RNAi)-mediated silencing of the gene targets. However, a limited number of reports documented silencing of plant endogenes or transgenes after direct foliar RNA application. This study analyzed the importance of physiological conditions (plant age, time of day, soil moisture, high salinity, heat, and cold stresses) and different dsRNA application means (brush spreading, spraying, infiltration, inoculation, needle injection, and pipetting) for suppression of neomycin phosphotransferase II (NPTII) transgene in Arabidopsis thaliana, as transgenes are more prone to silencing. We observed a higher NPTII suppression when dsRNA was applied at late day period, being most efficient at night, which revealed a diurnal variation in dsRNA treatment efficacy. Exogenous NPTII-dsRNA considerably reduced NPTII expression in 4-week-old plants and only limited it in 2- and 6-week-old plants. In addition, a more discernible NPTII downregulation was detected under low soil moisture conditions. Treatment of adaxial and abaxial leaf surfaces by brushes, spraying, and pipetting showed a higher NPTII suppression, while infiltration and inoculation were less efficient. Thus, appropriate plant age, late time of day, low soil moisture, and optimal dsRNA application modes are important for exogenously induced gene silencing.

Proportional Trends of Continuous Rainfall in Indian Summer Monsoon

A comprehensive study on the Indian summer monsoonal rainfall (ISMR) is performed in the light of decadal changes in the continuous rainfall events and the number of rainy days using 68 years (1951–2018) of gridded rain gauge data. Non-parametric Mann–Kendall’s test is applied on total rainfall amount, the number of rainy days, number of continuous rainfall events, and rainfall magnitude to find trends over different climatic zones of India for the two periods, 1951–1984 and 1985–2018. Our results found a decreasing trend for more than 4-days of continuous rainfall events during the recent 34 years (1985–2018) compared to 1951–1984. The rate of increase/decrease in extreme/continuous rainfall events does not follow a similar trend in number of continuous rainfall events and magnitude. Moreover, the rainfall is shifted towards a lesser number of continuous rainfall days with higher magnitudes during 1985–2018. During the crop’s sow season (i.e., the first 45 days from the onset date of Indian monsoon), the total number of rainy days decreased by a half day during the last 34 years. Over the Central and North East regions of India, the number of rainfall days decreased by ~0.1 days/yr and ~0.3 days/yr, respectively, during 1985–2018. Overall, the decreasing trends in continuous rainfall days may escalate water scarcity and lead to lower soil moisture over rain-fed irrigated land. Additionally, an upsurge in heavy rainfall episodes will lead to an unexpected floods. On a daily scale, rainfall correlates with soil moisture and evaporation up to 0.87 over various land cover and land use regions of India. Continuous light-moderate rainfall seems to be a controlling factor for replenishing soil moisture in upper levels. A change in rainfall characteristics may force the monsoon-fed rice cultivation period to adopt changing rainfall patterns.

Effects of temperature, soil moisture and light intensity on the temporal pattern of floral gene expression and flowering of avocado buds (Persea americana cv. Hass)

For ‘Hass’ avocado (Persea americana Mill.), low temperature is known to induce flowering, but effects of other environmental factors remain equivocal. In addition, documentation of interactions among environmental factors, floral gene expression and subsequent flower development is limited. Thus, in this research, the effects of environmental factors on the temporal expression patterns of genes related to flowering time, floral meristem identity and floral organ identity were quantified in buds relative to inflorescence number. ‘Hass’ avocado trees were subjected to four different environmental conditions: optimal growth condition (OGC) (warm temperature, well-watered, photosynthetic active radiation > 900 μmoles m–2 s–1), low temperature (LT), low soil moisture (LSM) or low light intensity (LLI) for 8 weeks, followed by OGC for 6 weeks. Bud expression of homologs of Arabidopsis thaliana flowering genes FLOWERING LOCUS T (FT), LEAFY (LFY), APETALA1 (AP1), APETALA2 (AP2), APETALA3 (AP3), PISTILLATA.1 (PI.1), AGAMOUS.1 (AG.1) and AGAMOUS.3 (AG.3) were quantified over time. Only buds of LT-treated trees flowered. At the start of the experiment (week 0), buds of all trees expressed PaLFY, PaAP1 and PaAP2. After 4 weeks of treatment, bud PaAP1 expression was greater than in week 0 and continued to increase through week 8 only in LT-treated trees, whereas by week 8 PaLFY expression increased in LT- and LSM-treated trees. By week 10 (2 weeks after transfer to OGC), bud PaFT expression increased only in LT-treated trees, followed by activation of downstream floral organ identity genes PaAP3, PaPI.1, PaAG.1 and PaAG.3 by week 12. For OGC-, LSM- and LLI-treated trees, bud PaAP1, PaFT, PaAP3, PaPI.1 and PaAG.1 expression remained low, with PaAG.3 transcripts undetected at week 12. These trees did not flower. Among environmental factors tested, only LT increased bud expression of both PaLFY and PaAP1, which likely conferred floral meristem determinacy since transfer of LT-treated trees to OGC did not prevent flowering but activated PaFT, downstream floral organ identity genes, and flowering. The results suggest ‘Hass’ avocado floral development is promoted by low temperature-dependent floral induction and warm temperature-dependent floral organogenesis.

Effect of Soil Moisture Level on the growth of the Giant African Land Snails, Archachatina marginata and Achatina achatina in different season.

This study focused on the evaluation of the effect of soil moisture on the feed intake and weight gain of the Giant African Land snails, Achatina achatina and Archachatina marginata in different seasons using a 2 x 2 x 4 factorial experiment with soil moisture at two levels (low 25ml of water/ week and high 100ml water/week), species at two levels (Achatina achatina and Archachatina marginata) and season at four levels (cold dry, hot dry, hot wet and cold wet) constituting the three factors. Result showed that there was a significant seasonal differences (P<0.001) for weekly feed intake of snails in which values of 3.85, 2.53, 3.88 and 4.44g were recorded in cold dry, hot dry, hot wet and cold wet seasons, respectively. Monthly weight gains of 5.41g recorded for Archachatina marginata was significantly higher (P<0.001) than the value of 1.94g recorded for Achatina achatina. There was significant interaction (P<0.001) between soil moisture level and species on monthly weight gains of the snails. The feed intake and weight gain of snails (4.28 g and 6.43 g) in the high soil moisture treatment was significantly (P<0.01) higher than those in the low soil moisture treatment (3.07 g and 5.30 g). In conclusion, it is evident that species, season and soil moisture level affected the feed intake and weight gain of the Giant African Land Snails

Drought-induced reduction in flower size and abundance correlates with reduced flower visits by bumble bees.

Reduced water availability can cause physiological stress in plants that affects floral development leading to changes in floral morphology and traits that mediate interactions with pollinators. As pollinators can detect small changes in trait expressions, drought-induced changes in floral traits could affect pollinator visitations. However, the linkage between changes in floral traits and pollinator visitations under drought conditions is not well explored. We, therefore, tested whether drought-induced changes in floral morphology and abundance of flowers are linked to changes in pollinator visitations. We conducted flight cage experiments with a radio frequency identification system for automated visitation recordings with bumble bees (Bombus terrestris) and common charlock (Sinapis arvensis) as the model system. In total, we recorded interactions for 31 foraging bumble bees and 6569 flower visitations. We found that decreasing soil moisture content correlated with decreasing size of all measured morphological traits except stamen length and nectar tube width. The reductions in floral size, petal width and length, nectar tube depth and number of flowers resulted in decreasing visitation rates by bumble bees. These decreasing visitations under lower soil moisture availability might be explained by lower numbers of flowers and thus a reduced attractiveness and/or by increased difficulties experienced by bumble bees in handling smaller flowers. Whether these effects act additively or synergistically on pollinator behaviour and whether this leads to changes in pollen transfer and to different selectionp ressures require further investigation.

Reducing N2O emissions with enhanced efficiency nitrogen fertilizers (EENFs) in a high-yielding spring maize system.

Enhanced efficiency nitrogen fertilizers (EENFs), including nitrification inhibitors (NIs) and slow-release fertilizer (SRF), are considered promising approaches for mitigating nitrous oxide (N2O) emissions while improving crop yield. This study investigated the combined application of EENFs with improved water and fertilizer management in an intensively irrigated spring maize rotation over five years in Northwestern China. High-frequency measurements of N2O fluxes were made throughout each year (both during crop growth and the fallow season) in five treatments: no N fertilizer as a control (CK), conventional N fertilization and irrigation (Con), optimum N fertilization and irrigation (Opt, 33% reduction in N fertilizer and 25% reduction of irrigation water), optimum N fertilization and irrigation with nitrification inhibitor (Opt+NI), and optimum N fertilization and irrigation with slow-release fertilizer (Opt-SRF). Annual mean cumulative N2O emissions reached 0.31±0.07, 3.66±0.19, 1.87±0.16, 1.23±0.13, and 1.61±0.16kg N2O-N ha-1 for CK, Con, Opt, Opt+NI, and Opt-SRF, respectively, with annual mean nitrogen use efficiency (NUE) of 36, 54, 61 and 59% for Con, Opt, Opt+NI, and Opt-SRF, respectively. The Opt, Opt+NI and Opt-SRF treatments significantly reduced cumulative N2O emissions by 49%, 66%, and 56% (P<0.05), respectively, and increased NUE by 51%, 70%, and 66% (P<0.05), respectively, relative to Con. However, mean above-ground N uptake (288-309kgN ha-1) and mean grain yields (12.7-12.8Mgha-1) did not differ significantly between the Con, Opt, Opt+NI, and Opt-SRF treatments during the five-year study. High N2O emissions mainly occurred within a few days of fertilization with irrigation, which could have been produced by microbially-mediated nitrifier or nitrifier denitrification processes. The fallow seasons had significantly lower cumulative N2O emissions, which were mainly attributed to the low temperature, low N inputs of crop residues, and low soil moisture conditions. Our study clearly indicated that the combined application of EENFs with optimum N fertilization and irrigation management can reduce environmental impacts while maintaining high crop yields in dryland regions such as Northwest China.

Cumulative Effect of Botanical Seed Pelleting and Foliar Spray on Morpho Physiological, Leaf Chlorophyll, Gas Exchange and Yield Parameters in Black gram

Background: Black gram is one of the important pulse crops of the world and India is the major producer and consumer of pulses in the world. One of the main reason for low productivity of pulses is that they are cultivated mostly in areas with low soil moisture and poor soil fertility. In order to overcome such adverse conditions, low-cost techniques like seed hardening/pelleting are preferred. Seed pelleting provides package of nutrients that influences seed or soil at the seed-soil interface. Since the cost involved is very less, an attempt has been made to study the effect of botanical seed pelleting and foliar spary on growth and yield parameters in black gram cv. CO 6. Methods: Field experiments were conducted to evaluate the cumulative effect of botanical seed pelleting with pungam leaf powder @ 150g kg-1 and foliar spray of prosopis and moringa leaf powders with different concentrations (2%, 4%, 6% and 8%) on morpho physiological, leaf chlorophyll, gas exchange and yield parameters in black gram cv. CO 6 in the study. The observations on morpho physiological, leaf chlorophyll, gas exchange and yield parameters were recorded, statistically analysed and discussed here.Result: From the results, it was found that among the treatments, seed pelleting with pungam leaf powder @ 150 g kg-1 + foliar spray of prosopis leaf powder @ 6% recorded higher morpho physiological parameters viz., plant height (48.73 cm), number of branches plant-1 (8.78), dry matter production (14.83 g plant-1), chlorophyll ‘a’ (1.03 mg g-1), chlorophyll ‘b’ (1.11 mg g-1) and total chlorophyll content (2.14 mg g-1), photosynthesis and transpiration rates (27.33 mg CO2 m-2 s-1 and 10.60 mg H2O m-2 s-1), intercellular CO2 concentration and stomatal conductance (274.30 µ mol mol-1 and 0.82 mol-2 s-1). This treatment also recorded lower number of days to first flowering (23.23 days), earliness in 50 per cent flowering (30.12 days) and also recorded higher yield parameters such as lengthier pods, more number of pods plant-1, pod yield plant-1, number of seeds pod-1, seed yield plant-1, seed yield ha-1 and hundred seed weight of 5.60 cm, 26.30, 8.20 g, 7.30, 5.30 g, 795.12 kg ha-1 and 5.83 g, respectively as compared to other treatments. To conclude, seed pelleting with pungam leaf powder @ 150 g kg-1 + foliar spray of prosopis leaf powder @ 6% proved to be the best in enhancing morpho physiological, growth and yield parameters.

Оценка климатических рисков в отношении транспортной инфраструктуры северных регионов России

Theme. Infrastructure of transport systems of the permafrost zone of Russia, operated in conditions of global warming. Objectives. To quantify the risks of disrupting the functionality of transport infrastructure facilities, taking into account the soil and natural and climatic features in the territory of their operation. Methodology. Modeling the temperature dynamics of the soil massif, including the upper seasonal thawed layer and the lower layer of permafrost soil, identifying changes in its strength and deformation properties under the accepted scenario of climatic changes, assessing the impact of changes in the soil massif on the operational state and safety of various types of infrastructure facilities of transport systems (taking into account the appearance of additional precipitation of thawing soil and a decrease in its bearing capacity), determination of the values of predicted risks on a scale that is uniform for all types of objects. Results. New data have been obtained on the negative consequences of climate change for the infrastructure of transport systems in the permafrost zone of Russia. Under fairly conservative assumptions about a warming of 2 degrees Celsius, the risk of functional impairment for the road profile is predicted to be from 86 to 294 points on a 1000-point scale, and climatic risks increase with an increase in the temperature of permafrost. The magnitude of the expected risks in relation to the aerodrome pavement is approximately at the same level; these two types of objects are distinguished by the greatest resistance to climatic changes. Pile foundations are subject to risk ranging from 143 to 529 points. The most vulnerable to warming are strip and columnar foundations, for which the lowest risk value obtained during modeling is 389 points, and under unfavorable conditions (high-temperature permafrost in combination with low soil moisture), the risk increases to the maximum possible value of 1000 points. Implications. The risks of disrupting the functionality of infrastructural objects of the permafrost transport systems, predicted at warming up to 2 degrees Celsius, should be considered significant. With risks up to 400 points (road profile, airfield coverage), it is advisable to limit ourselves to monitoring the current state of the facility and, if necessary, restore its functionality. With risks from 400 to 600 points, it is recommended, and in case of risks over 600 points, it is mandatory to carry out preventive engineering and technical measures aimed at stabilizing the temperature regime of soils and preventing a sudden loss of functionality of individual elements of the transport system.

Effect of conservation agriculture on soil hydrothermal regimes, crop evapo-transpiration and water productivity of wheat crop in the semi-arid region of North-Western India

Thrice replicated field trial was conducted to access soil hydrothermal regimes, crop evapotranspiration, water productivity, and crop productivity under different conservation agriculture practices in wheat compared with traditional conventional treatment. There were seven treatments: conventional treatment (CT), permanent narrow bed (PNB), permanent narrow bed with residue (PNB+R), permanent broad bed (PBB), permanent broad bed with residue (PBB+R), zero tillage (ZT) and zero tillage with residue (ZT+R). Soil moisture (0–60 cm) was found 13–22% higher under different residue treatments as compared to CT. PNB, PBB treatments had 10–20% lower soil moisture as compared to CT. The soil temperature (015 cm) on the PNB, PBB treatments remained 0.5–3.7°C significantly higher than the other treatments. The actual evapotranspiration (ETa) values were found higher under CT, ZT, and ZT+R treatments as compared to other treatments due to flood irrigation. PBB+R treatment had 23–27% higher water productivity in wheat as compared to the CT. Above-ground biomass, plant height, leaf area index, yield, and yield attributes had maximum values under PBB+R treatment. Grain yield in PBB+R was 1619% higher in the wheat crop as compared to CT. PBB+R management practice can be recommended for adoption by farmers for improving productivity under wheat crop in the semi-arid region of northwestern India.

ФОРМУВАННЯ МІКРОБІОТИ РИЗОСФЕРИ ПШЕНИЦІ СПЕЛЬТИ І ПИРІЮ СЕРЕДНЬОГО Й БІОЛОГІЧНОЇ АКТИВНОСТІ ЧОРНОЗЕМУ ОПІДЗОЛЕНОГО

Soil microorganisms play a leading role in the formation of the nutrient regime of the soil, which determines the level of future crop harvest. A complex system of soil-plant-microorganisms is formed, with the participation of which the creation and decomposition of organic matter, the circulation of substances in nature, the preservation of fertility and the creation of an optimal level of nutrients supply. The number of amonifiers in the rhizosphere of cereals changes under the influence of the plant species. The smallest number of amonifiers was noted in the rhizosphere of the Zorya Ukraine — 183.3  28,52, in the rhizosphere of Kernza® and Khors — 202,6  68,0 and 202,2  66,4, respectively, which exceeded the spelt indicator by 10,3–10,5 %. There were 47,5–48,0 103 CFU/g soil of nitrifiers in the soil of the fallow, Khors and Kernza®, in the Zorya Ukraine — 46,0 103 CFU/g soil due to higher aeration and low soil moisture. The difference between the data on cellulolytic microorganisms of the spelе rhizosphere and wheatgrass hybrids was 6,8–9,2 %. The biological activity of the soil is one of the most important indicators of its fertility and cultivation. The most informative indicator is the level of СО2 emission, On the variant the fallow is — 0,39 mg / dm2 per hour, in other variants 0,26–0,34 mg/dm2 per hour. Cultivation of spelt without fertilization leads decrease intensity of carbon release in the 1,5. The cultivation of perennial cereal crops allows maintaining this indicator at a higher level. The intensity of fiber decomposition in the soil of fallow and wheat-wheatgrass hybrids was 66–69 %, and with spelt — 58 %. The amonification capacity in the Zarya Ukrainy variant — 7 mg N-NH4/kg of soil, and with wheat-wheatgrass hybrids at the fallow level — 8–9 mg N-NH4/kg of soil. The same trend persisted with ratio to the opposite process — nitrification. The results of microbiological analysis of the soil selected for different grain crops indicate that the root exudates of plants create favorable conditions for the vital activity of microorganisms. Comparison of the state of populations from agricultural areas with the microbiota of the biocenosis indicates the importance of including perennial grain crops in the crop rotation, which will increase the number of microorganisms in the rhizosphere and improve the conditions for the passage of soil-forming processes.

Development and Testing Mounted Multi-use Agricultural Seedbed Preparation Machine for Egyptian Soils

The main purpose of this present study is to develop and to test mounted multi-use seedbed preparation machine to limit soil disturbances by decreasing the number of field passes by performing one operation or more from three different operations (ploughing, surface leveling, and soil finishing/smoothing). Manufactured machine consisted of a frame with three installed units. Developed multi-use seedbed preparation machine was evaluated against its ability to increase soil clods less than 100 mm with calculating the fuel consumed, effective field capacity, power requirement, energy requirement per unit area, and draft force. Maximum recorded value of percentages of clod mean weight diameter less than 100 mm was 79.8 % and it was recorded when all the three different parts separately and in sequence (A)+(B)+(C) were operated with forward speed of 2.6 km/h at 14.50 % soil moisture content. Fuel consumption increased with increasing the tractor forward speeds, and at lower soil moisture content and when adding more units to be operated with the chisel unit in one travelling pass. Maximum effective field capacity was 1 fed/h and it was achieved by using the developed machine either with chesil unit alone A or operating the machine with two units, chisel plough and the soil leveler A+C achieved by using at 6.9 km/h and after harvesting soybean with soil moisture content of 15.5 %. Operating the seedbed preparation machine with different combination parts gave higher values of powered required in corn harvested soil than soybean harvested soil

Lower soil moisture and deep soil temperatures in thermokarst features increase old soil carbon loss after 10 years of experimental permafrost warming

AbstractAlmost half of the global terrestrial soil carbon (C) is stored in the northern circumpolar permafrost region, where air temperatures are increasing two times faster than the global average. As climate warms, permafrost thaws and soil organic matter becomes vulnerable to greater microbial decomposition. Long‐term soil warming of ice‐rich permafrost can result in thermokarst formation that creates variability in environmental conditions. Consequently, plant and microbial proportional contributions to ecosystem respiration may change in response to long‐term soil warming. Natural abundance δ13C and Δ14C of aboveground and belowground plant material, and of young and old soil respiration were used to inform a mixing model to partition the contribution of each source to ecosystem respiration fluxes. We employed a hierarchical Bayesian approach that incorporated gross primary productivity and environmental drivers to constrain source contributions. We found that long‐term experimental permafrost warming introduced a soil hydrology component that interacted with temperature to affect old soil C respiration. Old soil C loss was suppressed in plots with warmer deep soil temperatures because they tended to be wetter. When soil volumetric water content significantly decreased in 2018 relative to 2016 and 2017, the dominant respiration sources shifted from plant aboveground and young soil respiration to old soil respiration. The proportion of ecosystem respiration from old soil C accounted for up to 39% of ecosystem respiration and represented a 30‐fold increase compared to the wet‐year average. Our findings show that thermokarst formation may act to moderate microbial decomposition of old soil C when soil is highly saturated. However, when soil moisture decreases, a higher proportion of old soil C is vulnerable to decomposition and can become a large flux to the atmosphere. As permafrost systems continue to change with climate, we must understand the thresholds that may propel these systems from a C sink to a source.

Production of Organic Fertilizers from Rocket Seed (Eruca Sativa L.), Chicken Peat and Moringa Oleifera Leaves for Growing Linseed under Water Deficit Stress

Linseed is an important industrial crop cultivated for its edible seeds and fiber linen. Organic fertilizers have beneficial effects on soil properties and quality of crops. Therefore, we conducted two field experiments during 2018–2019 and 2019–2020 to determine the effect of organic fertilizers on soil fertility, yield and fiber quality of linseed varieties Roshni, BL1 and Chandni under low soil moisture conditions. We prepared organic fertilizers from seed cake of Eruca sativa, leaves of Moringa oleifera and chicken peat in various combinations by composting method. The various formulations of organic fertilizers included OF1(1 kg seed cake of Eruca sativa), OF2 (1 kg seed cake of Eruca sativa + 1 kg chicken peat), OF3 (1 kg seed cake of Eruca sativa + 0.5 kg chicken peat + 0.25 kg Moringa oliefera leaves) and OF4 (1 kg seed cake of Eruca sativa + 0.250 kg chicken peat + 0.5 kg Moringa oliefera leaves). Compositional analysis of organic fertilizers indicated that OF3 and OF4 had higher and may potentially sufficient quantities of NPK and organic matter. Both of these fertilizers significantly improved soil total N, available P, K, Zn and Fe contents. Growth response of linseed varieties to organic fertilizers was evaluated under water deficit stress (40% field capacity of soil) at tillering stage for one month. Water stress had significantly adverse effects on plant height, production of tillers per plant, leaf relative water content (LRWC), number of capsules per plant, thousand seed weight, total seed yield, straw yield, fiber length and fiber weight of linseed varieties. However, the application of OF3 and OF4 significantly enhanced plant height, tillers production, LRWC, seed yield, straw yield, fiber length and fiber weight under water deficit stress. Water deficit stress also resulted in a significant increase in the content of phenolics of both the leaves and roots. For each measured quality parameter of linseed varieties, organic fertilizer treatments resulted in higher values than untreated and irrigated control. We concluded that organic fertilizers particularly OF3 and OF4 significantly improved soil fertility and minimized negative effect of water deficit stress on plant height, tillers production, LRWC, seed yield, straw yield, fiber length and fiber weight of linseed varieties.

Effect of soil moisture content and nitrogen fertilizer on survival, growth and some physiological characteristics of Platycladus orientalis seedlings

Given the important applications of oriental arborvitae (Platycladus orientalis /L./ Franco), we examined the interaction effects of soil moisture content (SMC) and urea fertilizer on survival, growth and some physiological characteristics of seedlings of this species. In this study, 270 uniform oriental arborvitae seedlings were transplanted in 2 kg containers filled with the top soil of the natural stand in Soorkesh forest reserve. After 2 months, 6 levels of SMC (100%, 75%, 50%, 25%, 15% and 10%) and 3 levels of urea [control: 0, low nitrogen (LN): 75 mg·kg&lt;sup&gt;–1&lt;/sup&gt;, and high nitrogen (HN): 150 mg·kg&lt;sup&gt;–1&lt;/sup&gt;] were used from June till the end of the first growing season in 3 replications and 5 seedlings per replication as subsamples. The results showed that all seedlings survived under SMC above 25% in control and urea fertilizer treatments. However, under 15% and 10% SMC, the seedling survival decreased significantly in control treatment, but adding urea fertilizer significantly increased the survival, especially in HN treatment. Growth and morphological properties of seedlings, including root and shoot length, number of first-order lateral roots and total biomass, showed a significant decrease at 75%. Seedling quality index gradually decreased with SMC reduction, but the addition of urea to the soil significantly increased it under all SMC treatments. The results also indicated that a decrease in SMC significantly decreased relative water content of leaves and total chlorophyll content, and urea fertilizer increased total chlorophyll under all SMC treatments, but it increased relative water content only at 100% to 25%. Moreover, water use efficiency of P. orientalis seedlings significantly increased under low soil moisture treatments, and urea significantly increased it, especially under HN treatment. In conclusion, urea fertilizer, especially in the higher amount (150 mg·kg&lt;sup&gt;–1&lt;/sup&gt;), improved growth and quality of seedlings under different soil moisture conditions, and increased their survival under severe drought.

Phenotypic Plasticity of Drought Tolerance Traits in a Widespread Eucalypt (Eucalyptus obliqua)

Long-term studies of tree responses to drought stress help us to understand the capacity of species to adapt to their environment. In this study, we investigated how Eucalyptus obliqua adjusts physiological and morphological traits in response to seasonal and multi-year droughts. We monitored physiological and morphological traits over multiple years in undisturbed control and throughfall reduction plots in a eucalypt forest in south-eastern Australia. The throughfall reduction treatment did not induce significantly lower soil moisture in the throughfall reduction plots compared with the control plots. However, natural variability in precipitation and evaporative demand induced drought stress of varying intensity each summer in all plots. We observed a significant relationship between seasonal precipitation and leaf pre-dawn water potential (ΨPD), with less precipitation over summer, resulting in a decline in ΨPD and drought stress when ΨPD fell below −0.75 MPa. Eucalyptus obliqua responded to short-term summer drought through rapid leaf osmotic adjustment which lowered the leaf water potential at the turgor loss point beyond the minimum leaf water potential. Morphological adjustments, such as the reduction of leaf area to sapwood area (higher Huber Value) were moderate during the measurement period and only occurred under severe drought stress (pre-dawn water potential &lt; −1.2 MPa). Overall, E. obliqua responded to short-term mild drought stress through physiological trait plasticity, while morphological adjustment only occurred under a more severe water deficit.

Simulated Winter Incubation of Soil With Swine Manure Differentially Affects Multiple Antimicrobial Resistance Elements.

Gastrointestinal bacteria that harbor antibiotic resistance genes (ARG) become enriched with antibiotic use. Livestock manure application to cropland for soil fertility presents a concern that ARG and bacteria may proliferate and be transported in the environment. In the United States, manure applications typically occur during autumn with slow mineralization until spring planting season. A laboratory soil incubation study was conducted mimicking autumn swine manure application to soils with concentrations of selected ARG monitored during simulated 120-day winter incubation with multiple freeze-thaw events. Additionally, the effects of two soil moistures [10 and 30% water holding capacity (WHC)] and two manure treatments [raw versus hydrated lime alkaline stabilization (HLAS)] were assessed. Fourteen tetracycline resistance genes were evaluated; tet(D), tet(G), and tet(L) were detected in background soil while swine manure contained tet(A), tet(B), tet(C), tet(G), tet(M), tet(O), tet(Q), and tet(X). By day 120, the manure-borne tet(M) and tet(O) were still detected while tet(C), tet(D), tet(L), and tet(X) genes were detected less frequently. Other tet resistance genes were detected rarely, if at all. The sum of unique tet resistance genes among all treatments decreased during the incubation from an average of 8.9 to 3.8 unique tet resistance genes. Four resistance elements, intI1, blactx–m–32, sul(I), erm(B), and 16s rRNA genes were measured using quantitative PCR. ARG abundances relative to 16S abundance were initially greater in the raw manure compared to background soil (−1.53 to −3.92 log abundance in manure; −4.02 to <−6.7 log abundance in soil). In the mixed manure/soil, relative abundance of the four resistance elements decreased (0.87 to 1.94 log abundance) during the incubation largely because 16S rRNA genes increased by 1.21 log abundance. Throughout the incubation, the abundance of intI1, blactx–m–32, sul(I), and erm(B) per gram in soil amended with HLAS-treated manure was lower than in soil amended with raw manure. Under low initial soil moisture conditions, HLAS treatment reduced the abundance of intI1 and resulted in loss of blactx–m–32, sul(I), and erm(B)] compared to other treatment-moisture combinations. Although one might expect antibiotic resistance to be relatively unchanged after simulated winter manure application to soil, a variety of changes in diversity and relative abundance can be expected.