Total Potassium Content Research Articles

Pecan Biomass and Dairy Manure Utilization: Compost Treatment and Soil In-Situ Comparisons of Selected Pecan Crop and Soil Variables

A compost program was developed on-farm, utilizing tree trimming biomass from a commercial pecan farm comprised of 14-year-old improved cultivar Western Schley pecan (Carya illinoinensis) tree stands. The direct soil application of shredded pecan tree biomass (P) and dairy manure (M) served as a standard on-farm practice. Three composts were produced using P and M with varying levels of other inputs and processing. The PM compost contained only P and M and its production included only weekly turning and watering. The other two composts included P, M, unfinished compost, and clay inputs, and either additional landscaping residues (A) (designated PM/A compost) or “green chop” (on-farm grown legumes, G) (designated PMG/A compost); production of PM/A and PMG/A composts included additional processing steps intended to improve compost quality per the recommendations of a compost consulting company. Soil samples were taken at three depths (0–15 cm, 15–30 cm, 30–61 cm) in November 2017 from the 1.3 ha study plot of trees. The standard practice and compost treatments were applied at approximately 18 t/ha in January 2018 and 2019 at a 15 cm depth. Soils were re-sampled at the end of the two-year study. Composts and soils were analyzed for: pH, sodium adsorption ratio (SAR), electrical conductivity, and total carbon, organic matter, magnesium, calcium, sodium, nitrate-N, total Kjeldahl nitrogen (TKN), available phosphorus, potassium, zinc, manganese, iron, and copper contents. Pecan tree leaf nutrient content, stem water potential, and leaf greenness were also measured one and two years after soil amendment application. While increases in several soil properties were observed with the treatments, only available phosphorus content was significantly different between pre and post at all depths. Electrical conductivity, TKN, Fe, Cu, SAR, and Na content showed significant differences in the upper soil layers. No differences in leaf properties were observed. This suggests that there are minimal differences in the outcomes for compost application compared to in-situ biomass application; additional compost inputs and processing did not provide additional short-term soil or plant benefits for pecan tree production. More work is needed to determine if there are long-term benefits to soil quality, plant health and performance, or carbon sequestration that impact the economic and environmental decision-making processes for composting and application of local organic wastes.

Biochar immobilized plant growth-promoting rhizobacteria enhanced the physicochemical properties, agronomic characters and microbial communities during lettuce seedling.

Spent mushroom substrate (SMS) is the by-products of mushroom production, which is mainly composed of disintegrated lignocellulosic biomass, mushroom mycelia and some minerals. The huge output and the lack of effective utilization methods make SMS becoming a serious environmental problem. In order to improve the application of SMS and SMS derived biochar (SBC), composted SMS (CSMS), SBC, combined plant growth-promoting rhizobacteria (PGPR, Bacillus subtilis BUABN-01 and Arthrobacter pascens BUAYN-122) and SBC immobilized PGPR (BCP) were applied in the lettuce seedling. Seven substrate treatments were used, including (1) CK, commercial control; (2) T1, CSMS based blank control; (3) T2, T1 with combined PGPR (9:1, v/v); (4) T3, T1 with SBC (19:1, v/v); (5) T4, T1 with SBC (9:1, v/v); (6) T5, T1 with BCP (19:1, v/v); (7) T6, T1 with BCP (9:1, v/v). The physicochemical properties of substrate, agronomic and physicochemical properties of lettuce and rhizospheric bacterial and fungal communities were investigated. The addition of SBC and BCP significantly (p < 0.05) improved the total nitrogen and available potassium content. The 5% (v/v) BCP addiction treatment (T5) represented the highest fresh weight of aboveground and underground, leave number, chlorophyll content and leaf anthocyanin content, and the lowest root malondialdehyde content. Moreover, high throughput sequencing revealed that the biochar immobilization enhanced the adaptability of PGPR. The addition of PGPR, SBC and BCP significantly enriched the unique bacterial biomarkers. The co-occurrence network analysis revealed that 5% BCP greatly increased the network complexity of rhizospheric microorganisms and improved the correlations of the two PGPR with other microorganisms. Furthermore, microbial functional prediction indicated that BCP enhanced the nutrient transport of rhizospheric microorganisms. This study showed the BCP can increase the agronomic properties of lettuce and improve the rhizospheric microbial community.

Effects of mixed substrates of different agricultural and forestry residues on the cutting seedlings of Thuja sutchuenensis.

To screen environment-friendly seedling cultivation substrates which could replace peat and with less cost, we compared the effects of different agricultural and forestry residue mixed substrates on cutting propagation of Thuja sutchuenensis, in an experiment following randomized block design. There were five types of mixed substrates, including peat + vermiculite + perlite (T1), edible mushroom residue (EMR) + vermiculite + perlite (T2), carbo-nized rice husk (CRH) + vermiculite + perlite (T3), EMR + slag + sawdust (T4) and CRH + EMR + slag (T5). The results showed that the bulk density of T3 was the lowest, followed by T2, which significantly differed from other mixed substrates. The non-capillary porosity of T2 was significantly greater than that of T1, while the capillary porosity and the total porosity of T2 was lower than T1 and T3, respectively. T2 had the highest contents of total nitrogen, total phosphorus, total potassium, alkali-hydrolyzed nitrogen, available phosphorus, substrate moisture and the highest pH, which differed significantly from other mixed substrates in most chemical indicators. The membership function values of rooting rate and growth indicators of cuttings with different mixed substrates were in order of T2 > T3 > T1> T5 > T4. Most indicators with larger grey relation values were physical indicators. The top five indicators were capillary water capacity, total potassium, field water capacity, maximum water capacity, and total porosity, with both capillary water capacity and total potassium content ranking first. In general, the physicochemical properties, rooting rate, and growth characteristics of cuttings under T2 were better than those of other mixed substrates. The capillary water capacity and total potassium were the main factors affecting rooting and growth of cuttings. At the early stage of cutting, the physical properties of mixed substrate had greater effect on rooting rate and growth of cuttings than the chemical properties. Overall, our results suggested that T2 should be preferred in the cutting propagation of T. sutchuenensis.

An Experimental Study to Improve the Nutrients and the Mechanical Properties of Copper Tailings Sand in China’s Arid Zone by Biomineralization of Locally Isolated Urease-Producing Bacteria

Microbially induced carbonate precipitation (MICP) technology is an environmentally friendly technique that can contribute to tailings consolidation and ecosystem restoration. Our study found that local MICP bacteria, Lysinibacillus fusiformis, could remediate copper tailings pollution at different slope positions (K1, K2, and K3) in arid areas. We analyzed the effect of MICP treatment on the slag from macro- to microscopic levels with a dissolution test, soil physical and chemical tests, wind tunnel testing experiments, and scanning electron microscopy (SEM). The results demonstrated that the MICP bacteria, L. fusiformis, effectively remodeled the slag structure, thereby preventing the diffusion of tailing slag caused by wind erosion. This structural remodeling resulted in a significant increase in slag strength (maximum strength: 2707 KPa) and an increased content of CaCO3. Furthermore, it led to a significant reduction in total salinity content (36.4–43.6%), pH (4.1–4.4%), and improvement in nutritional status (total potassium content (16–31.4%) and the available phosphorus content (2.1–2.3 times) of the tailings slag (p &lt; 0.05). There was also a 15% increase in urease and catalase activity in K1, a 7% increase in invertase activity in K3 (p &lt; 0.05), and a significant increase in carbon and nitrogen microbial biomass in K1, K2, and K3 (p &lt; 0.05).

Mapping Soil Organic Carbon in Floodplain Farmland: Implications of Effective Range of Environmental Variables

Accurately mapping soil organic carbon (SOC) is conducive to evaluating carbon storage and soil quality. However, the high spatial heterogeneity of SOC caused by river-related factors and agricultural management brings challenges to digital soil mapping in floodplain farmland. Moreover, current studies focus on the non-linear relationship between SOC and covariates, but ignore the effective range of environmental variables on SOC, which prevents the revelation of the SOC differentiation mechanism. Using the 375 samples collected from the Jiangchang Town near Han River, we aim to determine the main controlling factors of SOC, reveal the effective range of environmental variables, and obtain the spatial map of SOC by using the gradient boosting decision tree (GBDT) model and partial dependence plots. Linear regression was used as a reference. Results showed that GBDT outperformed linear regression. GBDT results show that the distance from the river was the most important SOC factor, confirming the importance of the Han River to the SOC pattern. The partial dependence plots indicate that all environmental variables have their effective ranges, and when their values are extremely high or low, they do not respond to changes in SOC. Specifically, the influential ranges of rivers, irrigation canals, and rural settlements on SOC were within 4000, 200, and 50 m, respectively. The peak SOC was obtained with high clay (≥31%), total nitrogen (≥1.18 g/kg), and total potassium contents (≥11.1 g/kg), but it remained steady when these covariates further increased. These results highlight the importance of revealing the effective range of environmental variables, which provides data support for understanding the spatial pattern of SOC in floodplain farmland, achieving carbon sequestration in farmland and precision agriculture. The GBDT with the partial dependence plot was effective in SOC fitting and mapping.

Soil Stoichiometry Characterization in the Oasis-desert Transition Zone of Linze, Zhangye

To investigate the changes in C, N, P, and K contents and ecological stoichiometry of desert oasis soils and to elucidate their ecological responses to environmental factors, 10 sample plots were selected in the Zhangye Linze desert oasis in the middle part of the Hexi Corridor, and surface soil samples were collected to determine the C, N, P and K contents of soils and to reveal the distribution characteristics of soil nutrient contents and stoichiometric ratios in different habitats and the correlation with other environmental factors. The results showed that:① the distribution of soil carbon was uneven and heterogeneous across sites (R=0.761, P=0.06). The highest mean value was 12.85 g·kg-1 in the oasis, followed by 8.65 g·kg-1 in the transition zone and 4.1 g·kg-1 in the desert. ② The content of total soil potassium did not vary significantly and was high among deserts, transition zones, and oases and low in saline areas. ③ The mean soil C:N value was 12.92, the mean C:P value was 11.69, and the mean N:P value was 0.9, all of which were lower than the global average soil content (13.33, 72.0, and 5.9) and the Chinese soil average (12, 52.7, and 3.9). ④ Soil water content was the most influential factor affecting C, N, P, K, and ecological stoichiometry characteristics of desert oasis soils, with a contribution of 86.9%, followed by soil pH and soil porosity, with contributions of 9.2% and 3.9%, respectively. The results of this study provide basic information for the restoration and conservation of desert and oasis ecosystems and establish a basis for future study of the biodiversity maintenance mechanism in the region and its correlation with the environment.

Bacterial Diversity Analysis and Screening for ACC Deaminase-Producing Strains in Moss-Covered Soil at Different Altitudes in Tianshan Mountains-A Case Study of Glacier No. 1.

The elevation of the snowline of the No. 1 Glacier in the Tianshan Mountains is increasing due to global warming, which has created favorable conditions for moss invasion and offers an opportunity to investigate the synergistic effects of incipient succession by mosses, plants, and soils. In this study, the concept of altitude distance was used instead of succession time. To investigate the changes of bacterial-community diversity in moss-covered soils during glacial degeneration, the relationship between bacterial community structure and environmental factors was analyzed and valuable microorganisms in moss-covered soils were explored. To do so, the determination of soil physicochemical properties, high-throughput sequencing, the screening of ACC-deaminase-producing bacteria, and the determination of ACC-deaminase activity of strains were performed on five moss-covered soils at different elevations. The results showed that the soil total potassium content, soil available phosphorus content, soil available potassium content, and soil organic-matter content of the AY3550 sample belt were significantly different compared with those of other sample belts (p < 0.05). Secondly, there was a significant difference (p < 0.05) in the ACE index or Chao1 index between the moss-covered-soil AY3550 sample-belt and the AY3750 sample-belt bacterial communities as the succession progressed. The results of PCA analysis, RDA analysis, and cluster analysis at the genus level showed that the community structure of the AY3550 sample belt and the other four sample belts differed greatly and could be divided into two successional stages. The enzyme activities of the 33 ACC-deaminase-producing bacteria isolated and purified from moss-covered soil at different altitudes ranged from 0.067 to 4.7375 U/mg, with strains DY1-3, DY1-4, and EY2-5 having the highest enzyme activities. All three strains were identified as Pseudomonas by morphology, physiology, biochemistry, and molecular biology. This study provides a basis for the changes in moss-covered soil microhabitats during glacial degradation under the synergistic effects of moss, soil, and microbial communities, as well as a theoretical basis for the excavation of valuable microorganisms under glacial moss-covered soils.

Correlation between soil environment and yield and quality of Sharen (Amomi Fructus) under different planting patterns

ObjectiveTo study the effects of soil environment on the growth, yield, and quality of Sharen (Amomi Fructus) under different planting patterns. MethodsSoil physical and chemical indices and enzyme activities in four periods including early flowering (March), full flowering (June), fruit ripening (September), and late fruit picking (December), were measured under three planting patterns including natural forest, greenhouse, and rubber forest in Xishuangbanna, China. The changes in soil indices during the growth periods of Sharen (Amomi Fructus) under different planting patterns were analyzed, and the differences in plant growth, yield, and quality under different planting patterns were explored. Pearson correlation analysis was used to analyze the relationship between soil indices and Sharen (Amomi Fructus) growth, yield, and quality. Principal component analysis was used to investigate the effects of soil environment under different planting patterns on Sharen (Amomi Fructus) growth, yield, and quality. ResultsThe soil moisture, available potassium content, and urease activity of the three planting patterns of Sharen (Amomi Fructus) increased initially and decreased afterwards throughout the year; pH and organic matter content showed little change in the whole year. Exchangeable manganese content and acid phosphatase activity gradually increased throughout the year. Hydrolyzed nitrogen content, exchangeable calcium content, available zinc content, protease activity, and sucrase activity decreased initially and increased afterwards throughout the year. Exchangeable magnesium content, available iron content, and catalase activity decreased annually. Total nitrogen content, total phosphorus content, and available phosphorus content fluctuated throughout the year. The total potassium content under natural forest and greenhouse planting decreased throughout the year, while the total potassium content under rubber forest showed an upward trend all year round. The organic matter content, total nitrogen content, total potassium content, available potassium content, available zinc content, urease activity, acid phosphatase activity, and catalase activity under greenhouse were significantly lower than those under natural and rubber forests (P < 0.05). Correlation analysis showed that plant growth, yield, and quality of Sharen (Amomi Fructus) were significantly correlated with soil organic matter, total nitrogen, hydrolyzed nitrogen, total phosphorus, available phosphorus, total potassium, available potassium, exchangeable manganese, exchangeable magnesium, exchangeable calcium, available zinc, urease, acid phosphatase, and invertase (P < 0.05). The results of the principal component analysis indicated that the soil environment of Sharen (Amomi Fructus) under natural forest was the best, followed by rubber forest and greenhouse. The order of its advantages and disadvantages is consistent with the growth index of Sharen (Amomi Fructus), but contrary to the yield of Sharen (Amomi Fructus), indicating that the soil environment directly affects the growth index and nutritional components of plants. ConclusionDifferent planting patterns of Sharen (Amomi Fructus) have different soil nutrient content, and the change rules in the growths period are not similar, with some differences. Soil indices have impacts on plant growth, yield, and quality of Sharen (Amomi Fructus). Soil ecological environment is positively correlated with the growth characteristics of Sharen (Amomi Fructus) plants, but has no direct correlation with yield and quality.

URINE SODIUM-TO-POTASSIUM RATIO DOES NOT ACCURATELY REFLECT DIETARY SODIUM-TO-POTASSIUM RATIO

Objective: High sodium intake is associated with an increased risk of cardiovascular disease, whereas a high potassium intake is associated with a reduced risk. Dietary counselling requires accurate estimation of sodium and potassium intake, but 24-hour urine sodium and potassium excretion demonstrated not to reflect actual intake. Urine sodium-to-potassium (Na/K) ratio is a promising alternative as it may be less affected by aldosterone-induced rhythmic changes in total body sodium and potassium content, is less influenced by incomplete urine collections, and incorporates both the effect of sodium and potassium. Our study assesses whether 24-hour urine Na/K ratio is superior in predicting dietary intake compared to 24-hour urine sodium or potassium excretion. Design and method: A post-hoc analysis was performed on data from the long-term sodium balance studies Mars105 and Mars520. Ten healthy participants received a diet with a known sodium and potassium content and collected 24-hour urine samples for 105 or 205 days. We calculated the log fold difference between dietary intake and urine content of sodium, potassium and Na/K ratio. We compared these estimates of accuracy using a mixed-effects model with a random intercept per subject. We analysed whether the accuracy differed among 6, 9 and 12 grams salt intake or was affected by the number of 24-hour urine collections. Results: Urine Na/K ratio underestimated dietary Na/K ratio with a median difference of -0.21 (IQR -0.47 to 0.09). Compared to sodium and potassium assessment, the Na/K ratio was significantly less accurate in predicting intake (Figure 1A). Only for the 6 gram salt phase the Na/K ratio did not perform significantly worse than sodium measurements. Increasing the number of 24-hour urine measurements to three or seven improved accuracy of the Na/K ratio, although it remained inferior to separate assessment of sodium and potassium excretion (Figure 1B). Conclusions: The 24-hour urine Na/K ratio is less accurate than 24-hour urine sodium excretion for estimation of dietary intake in a controlled setting.

Effects of Eudrilus eugeniae Worms and Cow Manure on the Vermicompost Process of Household Organic Waste

High population growth in developing countries also increases the amount of waste. Indonesia produces large amount of household solid waste production, namely 2.5 kg per day. Vermicompost is the best alternatives, the cheapest and does not harm the environment. In this study, the vermicompost method was used, worm weight and ratio affected the N, P, and K content in the fertilizer. The results of the sample test, namely the vermicompost time variable, the highest content was obtained at week 7 with N of 0.45%; P of 0.25%; and K by 0.23%. In the variable weight of worms, the highest weight of 300 grams of worms with N of 0.41%; P of 0.34%; and K by 0.23%; and the last variable is the ratio of cow dung and vegetable waste, where the highest content is at a ratio of 1:3 with N of 0.42%; P of 0.27%, and K of 0.22%. The test in this study was taken with 2 samples of the same variable and 1 different variable to determine the effect of these different variables on the N, P, and K content of liquid compost. Then the samples were tested for content using the macro-Kjedahl method to determine the nitrogen content, UV/Vis spectrophotometry to determine the phosphorus content, and AAS to determine the total potassium content.

Investigation of the response of sweet cherries to root mycorrhisation with biologics for sustainable horticulture development

Sustainable horticulture development is a priority area considering climate change, especially in the context of reduced water supply. The search for ways to regulate the resistance of fruit trees to stressors is an urgent issue for the world community. The use of beneficial microorganisms to inoculate plant roots helps reduce the use of synthetic substances and is an alternative for sustainable horticulture. The purpose of the study is to identify the specific features of the effect of root inoculation by mycorrhizal fungi on the reaction of sweet cherries to develop strategies for managing the production of fruit products. The study was conducted during 2018- 2020 in the sweet sweet cherry orchard of the southern steppe subzone of Ukraine. Such research methods as field, laboratory, biochemical, physiological, and statistical were used. The regularities of the influence of mycorrhizal fungi on the total moisture content and water-holding capacity of sweet cherry leaves were examined. In the first year of studies on endomycorrhizal root inoculation, these indicators were higher compared to the control group. The positive effect of endo-ectomycorrhiza on the waterholding capacity of sweet cherry leaves was elucidated. The total leaf surface and the content of green pigments in the leaves were determined as one of the main indicators of the photosynthetic potential of a fruit crop. The effect of inoculation of sweet cherry roots by mycorrhizal fungi on the ratio of chlorophylls (a/b) in leaves was established. The parameters of the content of total nitrogen, phosphorus, and potassium in sweet cherry leaves were determined. The use of mycorrhizal fungi increases the adaptive properties of sweet cherry trees to stressful factors, namely, arid conditions in the south of Ukraine. The research results can be used by fruit producers to improve climate-optimised technologies, which will substantially reduce risks and possible economic losses, and preserve biodiversity

Soil Quality Assessment of Several Kinds of Typical Artificial Forestlands in the Inner Mongolia Basin of the Yellow River

Located in the middle and upper parts of the Yellow River Basin, Qingshuihe County, Inner Mongolia, is a typical hilly and gully loess region and one of areas under the implementation of major ecological protection and restoration projects in the key ecological areas of Yellow River. Scientifically and accurately constructing a soil quality evaluation system for different types of artificial forest land and evaluating their soil quality are essential because they help optimize the structure of artificial forest land and improve the soil quality in the loess hilly area of Yellow River Basin. In this study, soil from four representative types of artificial forest land in the middle and upper reaches of the Yellow River Basin in Inner Mongolia was selected as the study object, with natural non-forest land as the control. Sixteen soil property indices in five classes, namely, soil texture, acid–base properties, moisture, pore, and nutrient, were screened using correlation analysis, minimum dataset (MDS), and principal component analysis methods, and an MDS of soil quality evaluation was constructed. Results showed that (1) the evaluation indices of artificial forest land soil quality based on the MDS included total potassium content, total phosphorus content, alkali-hydrolyzed nitrogen content, total nitrogen content, sand content, moisture content, and non-capillary porosity. (2) No significant differences were observed in the soil quality index among the MDS, total dataset, and significant dataset (SDS), all of which exhibited significant positive correlations. (3) The soil quality of the different types of forest land was sorted from high to low as follows: mixed coniferous and broad-leaved forests, larch forests, mixed arbor and shrub forests, Armeniaca sibirica forests, and natural non-forest land.

Suitable stocking density of fish in paddy field contributes positively to 2-acetyl-1-pyrroline synthesis in grain and improves rice quality.

Fragrant rice is increasingly popular with the public owing to its fresh aroma, and 2-acetyl-1-pyrroline (2-AP) is the main characteristic component of the aroma in fragrant rice. Rice-fish co-culture is an environmentally friendly practice in sustainable agriculture. However, the effect of rice-fish co-culture on 2-AP in grains has received little study. A conventional fragrant rice (Meixiangzhan 2) was used, and a related field experiment during three rice growing seasons was conducted to investigate the effects of rice-fish co-culture on 2-AP, as well as the rice quality, yield, plant nutrients, and precursors and enzyme activities of 2-AP biosynthesis in leaves. This study involved three stocking density treatments (i.e. 9,000 (D1), 15,000 (D2), and 21,000 (D3) fish fry per hectare) and rice mono-cropping. Rice-fish co-culture increased the 2-AP content in grains by 2.5%~49.4% over that of the mono-cropping, with significant increases in the early and late rice seasons of 2020. Rice-fish co-culture treatments significantly promoted seed-setting rates by 3.39%~7.65%, improved leaf nutrients and rice quality. Notably, the D2 treatment significantly increased leaf total nitrogen (TN), total phosphorus (TP), and total potassium (TK) contents and the head rice rate at maturity stage, while significantly decreased chalkiness degree. There were no significant difference in rice yield. Rice-fish co-culture had positive effects on 2-AP synthesis, rice quality, seed-setting rates, and plant nutrient contents. The better stocking density of field fish for rice-fish co-culture in this study was 15,000 fish/ha. This article is protected by copyright. All rights reserved.

Effects of different tillage systems and mowing time on nutrient accumulation and forage nutritive value of Cyperus esculentus.

Revealing the complex relationships between management practices, crop growth, forage nutritive value and soil quality will facilitate the development of more sustainable agricultural and livestock production systems. Cyperus esculentus is known as the king of oil crops and high-quality forage. However, there is little information about the effects of different planting modes {continuous cropping (CC)/rotation cropping (RC)} and initial mowing time on the plant nutrient accumulation and forage nutritive value. Here, in a field experiment, we designed two planting patterns, C. esculentus CC and C. esculentus - wheat RC. The leaves, tubers, roots, and soil samples were collected at three mowing time (on the 78th, 101th, and 124th days after seed sowing). Results revealed that RC significantly increased the total nitrogen (TN) and potassium (TK) content of the tuber (p<0.05), while significantly decreased the TN, total phosphorus (TP), crude protein (CP), and acid detergent fiber (ADF) contents of the leaves. Under the CC pattern, the TN, TP, and TK content of roots increased significantly on the 78th days after seed sowing, and the TK content of tubers increased significantly. Under the RC pattern, the ether extract (EE) content of tubers increased significantly on the 124th days after seed sowing, while the CP and TN content of leaves decreased significantly. Correlation analysis showed that soil pH was negatively correlated with TN content in leaves, tubers, and roots. The structural equation model showed that the soil pH directly affected the plant nutrient accumulation and forage nutritive value (β=0.68) via regulating these properties by changing soil available nutrients, anions, cations, and total nutrients. Overall, we propose that RC for C. esculentus-wheat is should not be recommended to maximize tubers and forage yield.

Root zone temperature regulates potassium absorption and photosynthesis in maize (Zea mays)

Affected by climate warming, the impact of crop root zone warming (RZW) on maize seedling growth and nutrient uptake deserve attention. The characteristics of K uptake in maize under root zone warming and the combined impacts of potassium deficiency and RZW are still unclear. The present study aimed to investigate the effects of RZW on potassium absorption and photosynthesis of maize seedlings under the difference in potassium. The results showed that RZW and low potassium treatment significantly affected root shoot development and photosynthetic physiological characteristics of maize seedlings. Moreover, the interaction of RZW and potassium content had striking influence on maize seedlings. Under the normal potassium with root zone medium temperature treatment, the development of maize was the most vigorous. Under the dual stress of high root zone temperature and low potassium, the root absorption area, total potassium content and root activity were significantly reduced, which then influenced the light energy use efficiency and dry matter accumulation. Securing the supply of potassium fertilizer under high root zone temperature stress is useful to alleviate the impact of high temperature stress.

Study on Distribution Characteristics of Mineral Nutrients in Fritillaria hubeiensis

The contents and correlation of various mineral elements in soil and roots, stems and leaves of Fritillaria hubeiensis were analyzed and evaluated to supply basis for diagnosis of soil mineral nutrition and rational fertilization of Fritillaria hubeiensis. The contents of Phosphorus, potassium, calcium, magnesium, iron, zinc, manganese and copper were tested by the inductively coupled plasma, and the results were analyzed by SPSS11.5 software. The total contents of manganese, phosphorus, potassium, calcium and magnesium in soil and roots, leaves and stems of Fritillaria hubeiensis were different with different cultivation bases. The order of Fe and Cu contents was root &gt; leaf &gt; stem. The distribution of Zn showed a trend of “root &gt; stem &gt; leaf.” Between potassium content of soil and root, it was a significant positive correlation. But there was a significant negative correlation between Zinc content of soil and root. The total contents of calcium and iron were positively correlated between roots and stems. The total contents of Phosphorus, potassium, magnesium and copper were positively correlated among stems and leaves, while the contents of Mn were positively correlated. Therefore, Fritillaria hubeiensis mainly regulates the amount of mineral nutrients through selective absorption.

Physical and Chemical Quality of Cow Feces Organic Fertilizer Produced by the Addition of Different Starters

The study aims to know the effect of different starters on the quality production of organic fertilizer. Three kinds of starters, EM-4 (P1), BM-4 (P2), and Petroganic (P3), were used in this study. The quality of organic fertilizer with a starter for the 28th day of composting was evaluated by physical and chemical parameters in triplicates. Based on the results, we showed the physical parameters of treatment compost P1, P2, and P3 are blackish brown, didn’t smell of stool, and are crumbly textured. The chemical parameters showed the content of C-organic from the treatments was 42.51%, 39.19%, and 35.74%, respectively, at the end of the composting process, while total nitrogen content was 4.71%, 9.47%, and 5.77%. The C/N ratio of each treatment, P1, P2, and P3, was 9.02, 4.17, and 6.20, while the total phosphor content was 0.092%, 0.15%, and 0.13%, respectively. Next, the total potassium content was 0.69%, 0.79%, and 0.77%, respectively, at the end of the composting process. The addition of different types of starters did not affect physical and chemical quality. In conclusion, EM-4, BM-4, and Petroganik can be used as alternative starters in producing organic fertilizer.

Canopy Gaps Control Litter Decomposition and Nutrient Release in Subtropical Forests

The formation of a canopy gap results in changes to the microenvironment which, in turn, affect litter decomposition and nutrient release. However, the mechanisms underlying these effects in differently sized gaps and non-gaps remain poorly understood. To address this gap in knowledge, we selected three large gaps (above 150 m2), three medium gaps (50–100 m2), three small gaps (30–50 m2), and three non-gaps with basically the same site conditions. We then used the litter bag method to investigate leaf and branch litter decomposition over a year in a Castanopsis kawakamii natural forest with the aim of characterizing the litter mass remaining and the nutrient release in canopy gaps and non-gaps. Our results revealed that the remaining litter mass of leaf and branch litter was lower in medium gaps compared to other gaps, and leaf litter decomposed faster than branch litter. Environmental factors were identified as the primary drivers of total carbon and nitrogen release during litter decomposition. Gap size (canopy openness), taxonomic Margalef index, the Brillouin index of soil microbes, soil total nitrogen content, soil pH value, and average air temperature were identified as the main factors driving carbon and nitrogen release from branch litter. In the late decomposition stage, the taxonomic Pielou index, soil total potassium content, soil water content, and average relative air humidity were the main drivers of nutrient release from branch litter. The soil water content and average relative air humidity were also found to be the main factors affecting the nutrient release from leaf litter throughout the different stages of decomposition. Overall, our study highlights the impact of canopy gaps on microenvironmental variation, taxonomic community diversity, and soil microbial functional diversity and how these factors ultimately influence litter decomposition and nutrient release. Our findings provide an important foundation for further research into soil nutrient cycling in subtropical natural forests.

Effects of Land-Use Types on Topsoil Physicochemical Properties in a Tropical Coastal Ecologically Fragile Zone of South China

Understanding the effects of land use on soil structure and nutrients is important for soil and water conservation in an ecologically fragile zone. This study was carried out to examine the variability of physicochemical properties in three different land use types: abandoned land (AL), eucalyptus plantation (EP), and road lawn (RL) sites at soil depths of 0–10 and 10–20 cm in the Leizhou Peninsula, a tropical coastal ecologically fragile zone of South China. Soil physicochemical property patterns exhibited extremely significant differences among the three land uses (p &lt; 0.001) at both soil depths. Soil nutrients, natural water content, and total porosity, from high to low, in the different land use types were RL, AL, and EP, while the bulk density, from high to low, was EP, AL, and RL. Soil total nitrogen, total phosphorus, total potassium, available potassium, exchangeable calcium, exchangeable magnesium, and natural water content exhibited significant differences (p &lt; 0.05) among the three land use types at soil depths of 0–10 and 10–20 cm, while no significant changes were detected regarding soil organic carbon, available phosphorus, and total porosity. The correlation between physical and chemical properties at the 10–20 cm depth (R = 0.97, p &lt; 0.001) was closer and more significant than that at the 0–10 cm depth (R = 0.95, p &lt; 0.01). Overuse of land (EP) without a rest in the ecologically fragile zone leads to soil erosion and compaction. Compared with natural restoration (abandoned land), artificial restoration (road lawn) can improve soil nutrient and water status more quickly, but cannot modify the soil organic carbon and porosity in the short term.

The altitudinal distribution characteristics of functional traits reflect the resource allocation strategy of Abies georgei var. smithii in southeast Tibet

To explore the adaptation strategies of the aboveground and underground functional traits of alpine plants along an altitudinal gradient, a typical stand of primitive dark coniferous forests (Abies georgei var. smithii.) in southeastern Tibet was taken as the research object in the present study. PCA and correlation analyses were carried out for different organ functional traits (19 key indicators in total), then RDA analysis was done in conjunction with 12 environmental factors. The variation characteristics of the functional traits of leaves, current-year twigs, trunks and fine roots in 6 continuous altitude gradients and the relationships between functional traits and environmental factors were explored. The results showed that soil organic carbon (SOC) may exert a positive effect on the construction of plant defense tissue via changes in functional traits, altitude (Alt) represents the primary influencing factor of wood density (WD) variation, particulate organic carbon (POC) content mainly affected fine root dry matter (RDWC) content and specific root length (SRL), and total potassium (TK) content was the main factor that affected fine root tissue density (RTD). Leaves, current-year twigs, and fine roots exhibited high production or nutrient acquisition capacity at an altitude of 4,000m and showed strong defense and relatively stable water and nutrient transport capacity. In conclusion, the ecological strategy of Abies georgei var. smithii. in Sejila Mountain was more conservative, and the optimal survival area of Abies georgei var. smithii. was located at 4, 000m on the shady slope of Sejila Mountain. It is of paramount significance for exploring the essence of terrestrial ecosystems and their functional processes in extremely high-altitude environments.