Poor Soil Quality Research Articles

Explaining the Soil Quality Using Different Assessment Techniques

Soil quality serves as the basis for both food security and environmental sustainability. To optimize production and implement soil management interventions, understanding the state of the soil quality is fundamental. Thus, this study was conducted to assess the soil quality of arable lands situated in the Nitisols and Luvisols using different assessment techniques. A total of 57 georeferenced soil samples were taken at a depth of 20 cm (18 from Nitisols and 39 from Luvisols land). The soil samples were analyzed for particle size distribution (PSD), texture, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (P), sulfur (S), exchangeable bases (calcium (Ca), magnesium (Mg), and potassium (K)), soil micronutrients (boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn)), and cation exchange capacity (CEC). The techniques used to estimate soil quality includes principal component analysis (PCA), a normalized PCA, and common soil parameters (soil texture, pH, OC, N, P, and K). The results were expressed in terms of soil quality index (SQI). In addition, the soil fertility/nutrient/index (NI) approach was used. The result showed that the SQI values using the common parameters approach were 0.17 and 0.30 for the lands belonging to Nitisols and Luvisols and categorized as very poor (<0.2) and poor (0.2–0.4) quality soils, respectively. PCA-SQI and normalized PCA-SQI values for lands in the Nitisols were 0.36 and 0.42, while for Luvisols they were 0.38 and 0.40, respectively. The soil quality of lands in the Luvisols was rated low (0.38–0.44), while lands in the Nitisols qualified under very low (<0.38) and low soil quality, respectively. In addition, the value of 1.42 and 1.78 in their order for lands belonging to Nitisols and Luvisols were recorded using the NI method that indicated low and medium soil quality. In conclusion, PCA and common soil parameters techniques regardless of soil types offered consistently similar information and could be taken as useful techniques for aiding soil management interventions. Furthermore, the result also calls for the need for applying soil management practices.

Effect of Some Soil Mineral Levels on Their Contents in Different Plant Parts and on the Yield of Chickpea-Rhizobium Symbioses

Chickpea is a legume with high nutritional value. It is mainly grown in arid and semi-arid areas soils, which are characterized by a deficiency in mineral elements, a severe water deficit and a poor soil quality. Our work aims to evaluate the effect of different mineral elements in the soil on nodular biomass, growth and yield of chickpea. The physico-chemical analyses of the soil and the agronomical and physiological parameters showed that the level of available phosphorus in the soil positively affected the growth parameters in the chickpea studied plants. Our results also confirmed the positive effect of adequate plant P nutrition on yield. Indeed, among the studied fields, agricultural soil 7 presented the highest potassium content and seeds yield (12.87 mg/g DM and 62 seeds per plant, respectively). In parallel, soil 7 recorded the highest value of available phosphorus 23.52 ppm. On the contrary, soil 5 was the least rich in P content (6.73 ppm). A positive correlation was recorded between the sodium concentration in the soil and in the aerial parts (<i>r </i>=0.73). The results also showed that the aerial part was richer in calcium than the root part and the nodules. Moreover, other positive correlations were recorded between the calcium concentration in the soil and in the aerial part and in the root part (<i>r </i>=0.76 and <i>r </i>=0.54; respectively).

First report of Colletotrichum truncatum causing anthracnose of dragon fruit (Hylocereus spp.) in India.

Dragon fruit (Hylocereus spp.) is gaining popularity due to high net return, medicinal importance and ability to survive under less water and poor quality soils. In year 2020 and 2021, H. undatus and H. polyrhizus plants at research field of ICAR-National Institute of Abiotic Stress Management, Baramati (18°09'30.62″N, 74°30'08″E) were affected with anthracnose disease. Out of 340 plants, 60 were symptomatic, showed disease severity up to 25 to 30%. Intermittent raining in July to September and untimely rain in November, 2021 favored the disease. Infected cladodes showed reddish to dark-brown, sunken lesions, with chlorotic haloes later converted to mature necrotic patches with prominent black acervuli. On fruits, small, light brown spots quickly turned to sunken water-soaked lesions with concentric rings of black acervuli. Infected stems were collected randomly from different plants. For pathogen isolation, lesion edge tissues (5 to 10 mm2) were excised and disinfected with 1% Sodium hypochlorite (2 min) followed by triple rinsed with sterilized water and plated on potato dextrose agar (PDA) amended with Streptomycin sulphate (30 mg/L) for 4 days at 27 ± 2°C with a 12 h photoperiod. Purified colonies of three isolates 2CT, 6CT, D6CT were obtained from successive isolation attempts. Colonies were round with smooth margins, initially pale white mycelia that changed to dark gray with pinkish-orange conidial masses. Average colony diameter was 58.3 mm at 7 DAI. Conidia were single-celled, hyaline, slightly curved, tapered tip and truncate base, with an oil globule at center. Average conidia size (n=50) was 25.7 (±2.3) μm × 3.7 (±0.2) μm, L/W ratio=6.9. Conidia were initiated from an acervular conidiomata with intermittent dark brown, septate, straight, pointed setae 114 (±35) μm long × 4.5 (±1.1) μm wide. Appressoria were dark brown, lobate or round, mostly in groups, measuring 11 (±2.4) × 6.6 (±0.8) μm. Morphological characters were consistent with Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore (Damm et al. 2009). For molecular identity of three isolates, partial internal transcribed spacer (ITS) region, actin, β-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified with ITS1/ITS4, ACT512F/ACT783R, BT2A/BT2B, and GDF1/GDR1 primers, respectively. Sequences were deposited in GenBank (ITS: OK639098 to OK639100; Actin: OM927967, OM927968, ON099061; TUB2: OM927969, ON099062, ON099063; GAPDH: ON099064, ON099065). A maximum likelihood phylogenetic tree based on all sequenced loci in MEGA11 shows the clustering of present isolates in the C. truncatum clade. For pathogenicity, 4 month old unwounded stems of H. undatus and H. polyrhizus were inoculated with a spore spray (1x106/ml conidia) of C. truncatum. For each isolate, three plants were inoculated. Plants inoculated with sterilized water represented the negative control. Inoculated and control plants were kept separately at 25 ± 2°C temperature and >85% relative humidity. Inoculated plants showed minute, sunken, water soaked, reddish brown spots which were converted to sunken patches with black acervuli at 15 DAI. No symptoms were observed in the negative control. Pathogenicity test was repeated twice and the pathogen was re-isolated from symptomatic stems showed similar morphology with C. truncatum. Based on morphological and molecular characteristics and pathogenicity test, pathogen identified as C. truncatum. Previously, dragon fruit anthracnose caused by C. truncatum was reported from China (Guo et al. 2014) and Malaysia (Vijaya et al. 2015). To our knowledge, this is the first report of C. truncatum cause of dragon fruit anthracnose in India. Detailed pathogen diagnostics may help in formulating effective, on time, appropriate disease management strategies.

Production of Summer Vegetables Using Conservation Agriculture Techniques: Experiences from Northern Bangladesh

Poor soil quality and decreasing crop yields brought on by ongoing monocropping in the fields of small-scale farmers in Bangladesh have demanded a search for sustainable production methods that are more resource efficient and environmentally friendly. Conservation agriculture is such a beneficial approach that effectively addresses crop productivity and soil quality enhancements using locally available resources. Therefore, the objective of the study was to determine the impacts of conservation agricultural practices on the growth and yield of summer vegetables cultivated in the northern region of Bangladesh. The study was carried out at farmers field situated in the Chilmari upazila of Kurigram district using the Randomized Complete Block Design (RCBD) with three replications during July to September 2020. The trial vegetables, i.e., Red amaranth, Kangkong and Indian spinach had showed the better yield of 4.95 t/ha, 14.5 t/ha and 19.5 t/ha in compared with traditionally cultivated vegetable cultivated methods in the farmers field, according the conservation agriculture method had enhanced vegetable yield. As part of conservation agriculture practices, soil organic matter content, total nitrogen, phosphorus, and potassium levels, as well as pH for better crop production, were all positively increase with the implications of conservation techniques like, adding organic manure, minimal tillage, permanent crop residues and crop rotation. Therefore, the study came to the conclusion that traditional agriculture would need to adopt conservation agriculture methods in order to produce more food while using fewer resources and doing so in a more efficient manner while having the least possible negative effects on the environment.

Organic Fertilizer Sources Distinctively Modulate Productivity, Quality, Mineral Composition, and Soil Enzyme Activity of Greenhouse Lettuce Grown in Degraded Soil

Intensive greenhouse vegetable production is often associated with a decline of crop productivity due to the increase of soil salinity and/or a reduction of biological fertility. The aim of the current work was to assess the effects of three organic fertilizers on morpho-physiological and agronomic traits of greenhouse lettuce as well as soil enzyme activity under poor soil quality conditions. The tested organic fertilizers (poultry manure, vinasse-based fertilizer, and insect’s frass fertilizer) were applied pre-planting at the same equivalent nitrogen (N) rate (90 kg N ha−1). Laboratory incubation assay results showed that vinasse-based fertilizer was the most suitable fertilizer in supplying the mineral N in the short term. All fertilizers increased shoot fresh and dry weight compared to unfertilized control with a more pronounced effect (+75%) with vinasse-based fertilizer and insect’s frass. Insect frass reduced by 27% the leaf nitrate concentration in comparison with the other treatments. The toxic heavy metal Pb was 46% lower in all organically fertilized lettuce leaves. Soil enzymatic activities of acid phosphatase, alkaline phosphatase, arylsulfatase (ArS), N-acetyl-β-D-glucosaminidase (NAGase), dehydrogenase, and total hydrolase (THA) were enhanced by poultry manure and insect’s frass in comparison with unfertilized control while vinasse-based fertilizer increased ArS, NAGase, and THA. Taken together, our data demonstrate that the application of organic fertilizers especially vinasse-based fertilizer and insect’s frass during intensive crop production is a suitable approach for mitigating the negative impact of soil salinity, enhancing soil biological fertility, and improving agronomic performance of greenhouse lettuce.

Factors Driving Jute to Maize Shift in Uttar Dinajpur, West Bengal

Jute is an important crop that contributes a pivotal role in the economy and supports the livelihoods of the farmers of the Northern part of West Bengal. However, farmers in the region are gradually shifting away from traditional jute cultivation to adopting maize as their preference and the study investigated the factors influencing transformation. Responses were collected from 60 farmers of Chopra Block using a structured interview schedule during the peak season of maize cultivation in 2019. Principal Component Analysis was used to extract significant factors explaining the motives behind farmers’ preference for maize over jute crops. The study envisages that the factors including lack of capital, remunerative market price, high labor costs, poor soil quality and inadequate irrigation water, unavailability of improved seed varieties, high input costs, and inadequate market facilities are the key factors for discouragement of cultivation of jute. The government should develop some supportive infrastructure like providing high-quality maize seeds, conducting awareness programs to educate the farmers about the benefits and byproducts of maize, and offering knowledge about export and import markets. Capacity building and extension approaches can aid the transition and foster positive contributions to the agricultural sector of the locality.

Guayule as an alternative crop for natural rubber production grown in B- and Se-laden soil in Central California

The potential of growing guayule ( Parthenium argentatum A. Gray) as an alternative crop for saline, boron- and selenium-laden soils in the Westside of central California was evaluated in both greenhouse and drainage sediment field experiments. In the greenhouse experiment, salt and boron (B) tolerance and selenium (Se) accumulation were evaluated in guayule accessions AZ-1 thru AZ-6 grown in saline soil and irrigated with simulated saline drainage water. The guayule accessions AZ1, AZ5, and AZ6 tolerated salinity and B levels better than the others. Consequently, AZ1, AZ5, and AZ6 were then planted in field sediment plots with slight salinity and moderate B levels. In both greenhouse and field studies, concentrations of Se, B, and Na in the leaves were as high as 0.6–8 mg/kg dry weight (DW), 2000 mg/kg DW, and 17,500 mg/kg DW, respectively, in both experiments. In both experiments, concentrations of rubber and resin ranged from 4 to 14 w/w% in the stems, and applied salinity increased rubber and resin production in some accessions. This two-phase study provides additional evidence for guayule accessions (AZ1–6) as a promising rubber-producing crop that tolerates saline irrigation water in poor quality soils. In addition, guayule may be useful in the gentle phytoremediation of Se in poor quality soils or in soils irrigated with Se-laden drainage water. • Guayule AZ accessions grown under saline, B- and S- laden conditions were evaluated. • Guayule’s tolerance to salinity, B, and Se in soil and irrigation varies by accession. • Boron, Se, and Na accumulation mostly takes place in leaf tissue. • Natural rubber and resin were not negatively affected by slight to moderate salinity. • Accession AZ5 was best suited for salinity and B.

Modeling of Irrigation Water Demand for Sustaining Crop Yield in Saline Environment

Increasing the productivity of water and making safe use of poor quality water in agriculture will play a vital role in easing competition for scarce water resources prevention of environmental degradation and provision of food security. The purpose of this study is to cover the crop water demand and supply gap with the management strategies. The comparison of actual water supplies and demand, i.e. crop water demand has been calculated and found that demand is more than supply. The daily reference evapotranspiration for Bhutana distributory is estimated using pan-Montieth method in CROPWAT model and crop-water demand has also been calculated using CROPWAT model. The supply shortfall in total Rabi seasons is 329.5 mm in 2009-10 and 162.2 in 2010-11. This gap is met by pumping ground water. Different scenario is generated after canal supply gap analysis because supply is less and demand is more and at the same, ground water quality is not so good. In some places, there is a problem of salinity or sodicity. Twelve point have been selected for soil sample from different locations of Butanadistributory. The result revealed that EC, SAR, RSC varies from 1.5 g/kg, 2.7-20 (mmoles kg-1)0.5 , 0- 8.8 mg/l. The best management strategies such as growing salt tolerant crops varieties and proper irrigation scheduling with effective conjunctive use of multiquality irrigation water, and pre-sowing water management was suggested for various scenarios of deficit canal water supply, poor soil and ground water quality, and water logging conditions for growing more food with less water of good/poor quality. This study will be helpful for engineers, researchers and farmers in taking decision on utilization of ground water, which will minimize their yield losses in scarce water supply and marginal quality of ground water.

Study of Tree Diversity and Biomass in Natural and Managed Site of Ridge Forest Ecosystem, Delhi Forest, India

Tree diversity and biomass (above and below-ground) were studied in natural and managed sites of Delhi Ridge Forest. The study was conducted in the Northern Ridge (NR) and South-Central Ridge (SCR) of the forest ecosystems. In the natural site of both the ridges, Prosopis juliflora (IVI= 105) was the dominant species due to its invasive nature. Eucalyptus tereticornis (IVI =41.7) and Pongamia pinnata (IVI= 63.5) was were dominant species in the managed site of NR and SCR, respectively. Rare species in the natural site was Wrightia tinctoria. In managed site, Thuja orientalis (IVI=4.08) and Ficus bengalensis (IVI= 4.6) were rare. The maximum biomass was found in aboveground biomass of the natural site of Delhi NR forest i.e. aboveground biomass (AGB) ranged was from 44.59 Mg ha-1 to 89.99 Mg ha-1 while the belowground biomass (BGB) was 17.29 ranged from 9.16 Mg ha-1 to 17.29 Mg ha-1. The least AGB was in the managed site of SCR (44.59 Mg ha-1). The total biomass of the NR ranged between 70.35 to 107.28 Mg ha-1. In SCR, it ranged between 53.75 to 96.22 Mg ha-1 which was low as compared to NR due to high human disturbance and poor soil quality. AGB and tree density was found to be maximum in 10-30 cm diameter class in all the sites of Ridge Forest. Prosopis juliflora was the most important tree species in ridge ecosystem as it allocated approximately 50% of the total biomass. Trees of Delhi ridge forest falls under lower diameter classes due to disturbance regime. Variations in species composition, density, diameter distributionpattern, biomass and Carbon stock in the Northern and South-Central Ridge were attributed to two different forest management practices adopted. Hence, both the Ridge Forest had potential for carbon sequestration due to presence of large number of trees belonging to small dbh classes.

Application of biochar and polyacrylamide to revitalize coastal saline soil quality to improve rice growth.

Poor soil quality is affected by salinity, which limits land productivity and sustainable agricultural development in coastal China. Hence, it is essential to choose suitable and efficient approaches to revitalize coastal saline soil quality and improve agricultural productivity. Biochar and polyacrylamide (PAM) have been widely applied as soil amendments to enhance soil structure, but the interactive effects of biochar and PAM on rice growth are unclear. The experiment described in this study was conducted over five consecutive growing seasons (from 2016 to 2020) with biochar (at 0, 32, and 79 t/hm2) and PAM (at 0, 0.6, and 1.6 t/hm2) applications to study the effects of amendments on soil properties, rice photosynthesis, and rice yield in coastal saline land. The soil property results showed that wheat straw biochar and PAM lowered soil total salt and bulk density, but increased the soil organic matter (SOM), mean weight diameter of water-stable aggregates (MWD), and macroaggregate (> 0.25 mm) content. The application of either biochar or PAM increased the rice net photosynthetic rate, transpiration rate, and stomatal conductance. The combined application of 32 t/hm2 biochar + 0.6 t/hm2 PAM increased the net photosynthetic rate by 26.0% and the transpiration rate by 24.8% relative to the control. The application of 32 t/hm2 biochar and 1.6 t/hm2 PAM significantly increased the rice grain yield. The path analysis model showed that spikelets per panicle and canopy gross photosynthesis had strong and significant positive effects on grain yield, whereas soil total salt had a negative effect on grain yield. The combined application of 32 t/hm2 biochar + 0.6 t/hm2 PAM was identified as the most effective for rice growth. Biochar and PAM amendments at an optimal level may enhance soil properties by reducing salinity. These findings indicate that biochar and PAM have the potential to remediate coastal saline soil quality and the environment, which would simultaneously increase the sustainable use of coastal land resources and food production to preserve the ecological environment.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-23511-w.

Do Disease and Pest Control Outsourcing Services Reduce Arable Land Abandonment? Evidence from China.

Arable land abandonment has been occurring in China in recent years. Although an emerging number of studies have investigated the impacts of urbanization and labor migration on arable land abandonment, little is known about what roles agricultural outsourcing services play in reducing arable land abandonment. Based on the data from the China Labor-force Dynamics Survey (CLDS) in both 2014 and 2016, this study employs a two-stage least squares method to address the potential endogeneity issue and sheds some light on the impact of agricultural outsourcing services for controlling disease and pests in arable land abandonment in China. The empirical results show that disease and pest control outsourcing services (DPCOS) significantly decrease the size of household-level arable land abandonment by 6.59% on average. More specifically, DPCOS mainly reduce the arable land abandonment in regions with the labor shortages, while this does not lead to a significant decrease in arable land abandonment in regions characterized by poor soil quality and steep slopes. Therefore, we may conclude that DPCOS could contribute to the reuse of farmlands suitable for cultivation and the exit of farmlands unsuitable for cultivation.

Assessment and Analysis of Soil Quality in an Industrial Zone from Lima, Peru Using the Grey Clustering Method

Within the district of Ventanilla there are many lead smelting companies, which emit gases containing heavy metals that, when transported to human settlements, could be causing damage to the health of the population, mostly harming young children. At present, the evaluation of soil quality involves the monitoring of various indicators that are analysed independently, leaving aside the systemic approach in which the elements interact and often restrict each other, making the analysis very complex. In this sense, a superior analysis system is proposed based on the Grey Clustering method, which is based on the theory of grey systems, an artificial intelligence approach that allows for an integral evaluation and takes into account the high degree of uncertainty present in the environment. The proposed methodology was used for the study of soil quality in the industrial park of the district of Ventanilla - Mi Perú, specifically in 3 Areas of Potential Interest (API): "Mercado Virgen de Guadalupe", "Patio de La I.E.P. Arturo Padilla Espinoza" and "AA.HH. Las Casuarinas". The results of the evaluation of soil quality using the Grey Clustering method showed that 40% of the total number of monitoring points have very poor soil quality, with the Virgen de Guadalupe Market area having 75% of the monitoring points with very poor soil quality. Finally, the present study can be of great use to the competent authorities related to the surveillance and monitoring of soil quality, as well as the health of the nearby population in order to make decisions on the control of nearby industrial activities.

INVESTIGATING CAUSES OF FLEXIBLE PAVEMENT FAILURE: A CASE STUDY OF THE BAKO TO NEKEMTE ROAD, OROMIA, ETHIOPIA

Most of the roads constructed in Ethiopia fail prematurely before serving the design life due to various causes arising from many factors. One of the roads that failed before reaching its design lifetime is the Bako to Nekemte Trunk Road. This road was constructed and opened to traffic in 2013. The design pavement life was estimated at 20 years. However; pavement failures have manifested since 2014 after it was opened for traffic. The main objective of this research was to investigate the cause for the failure of flexible pavement on the Bako to Nekemte road segment. To achieve this objective, the study was followed by the experimental research type and purposive sampling method. Also, field observation and pavement condition survey methods for data collection were used. The asphalt, base course, subgrade, and sub-base layer material sampled from the road segment are the material used for this study. Different pavement failures such as rutting, pothole, alligator cracking, raveling, edge cracking, depression, and corrugation were observed along the road section. For estimations of pavement condition index, the road was divided into five different sections based on distress densities, which were measured during the pavement condition survey. From those five sections, four sections were selected for the determination of the Pavement Condition Index (PCI). Using systematic random sampling 159 sample units were evaluated for Pavement Condition Rating (PCR) and the result shows 1.89% excellent, 8.18% very good, 20.13% good, 31.45% fair, 18.87 % poor, 18.24% very poor, and 1.26% failed. Based on PCI value, samples of pavement layer were taken from failed surface condition (1), poor surface condition (2), and none distressed area (1) for comparison purposes. Different quality tests like Atterberg limit, wash gradation, soil classification, compaction test, California Bearing Ratio (CBR), Los Angeles Abrasion (LAA), Flakiness Index ( FI), Aggregate Crushing Value (ACV), Ten percent fines value (TFV), bitumen content, and gradation of asphalt were carried out. The results of these tests were compared with ERA specifications to identify the probable cause of pavement failure. The study found that the cause for failure of flexible pavement in the case of Bako to Nekemte was: insufficient and absence of side drainage structure, traffic loading, poor gradation of base course and sub-base material, and poor quality of subgrade soil. The study also recommended that the road urgently needed routine maintenance as a treatment option to reduce further deterioration and extend its service time.

Soil Quality Analysis for Dryland Agriculture with Variation of Fertilization and Plant Rotation in Argomulyo District, Salatiga City

The study aim is to analyze soil quality for dryland agriculture with variations in fertilization and plant rotation in Argomulyo sub-district, Salatiga city. This study took samples on dryland agricultural land in Ledok Village by taking sample points using random sampling with a cluster sampling pattern by dividing them into 4 clusters. The Step of the research are field and laboratory observation to know the soil pH and moisture, also to determine the soil value and cation test, respectively. Next is the interview step to know the effect of fertilization and plant rotation variation. This research uses quantitative description analysis techniques. Based on the field observation was obtained the cluster 2 has pH value around 6.5 in the category slightly acidic. Then, for cluster 1,3, and has 4 neutral pH category in the range 6.6 – 7.5. The humidity of clusters in the dry category is in the range of 0 - 30%. Laboratory observation shows cluster 3 has a lower resistance around 8.1KW and has the best cation exchange capacity (CEC) test compared with other clusters. Based on the results of interviews, cluster 2 received organic fertilization and crop rotation occurred. Clusters 1 and 4 have not received any planting activity since October 2020. Meanwhile, fertilization in cluster 3 uses inorganic fertilizers. So Cluster 2 soil quality is better than the other three clusters due to organic fertilization and plans rotation so that the soil nutrients become stable. Cluster 1 has poor soil quality due to variations in inorganic fertilization, neglecting the soil, and being planted Manihot esculenta which impacted the reduction in the amount of nitrogen and phosphorus in the land.

Genetic and phenotypic diversity of microsymbionts nodulating promiscuous soybeans from different agro-climatic conditions

BackgroundGlobal food supply is highly dependent on field crop production that is currently severely threatened by changing climate, poor soil quality, abiotic, and biotic stresses. For instance, one of the major challenges to sustainable crop production in most developing countries is limited nitrogen in the soil. Symbiotic nitrogen fixation of legumes such as soybean (Glycine max (L.) Merril) with rhizobia plays a crucial role in supplying nitrogen sufficient to maintain good crop productivity. Characterization of indigenous bradyrhizobia is a prerequisite in the selection and development of effective bioinoculants. In view of this, bradyrhizobia were isolated from soybean nodules in four agro-climatic zones of eastern Kenya (Embu Upper Midland Zone, Embu Lower Midland Zone, Tharaka Upper Midland Zone, and Tharaka Lower Midland Zone) using two soybean varieties (SB8 and SB126). The isolates were characterized using biochemical, morphological, and genotypic approaches. DNA fingerprinting was carried out using 16S rRNA gene and restricted by enzymes HaeIII, Msp1, and EcoRI. ResultsThirty-eight (38) bradyrhizobia isolates obtained from the trapping experiments were placed into nine groups based on their morphological and biochemical characteristics. Most (77%) of the isolates had characteristics of fast-grower bradyrhizobia while 23% were slow-growers. Restriction digest revealed significant (p < 0.015) variation within populations and not among the agro-climatic zones based on analysis of molecular variance. Principal coordinate analysis demonstrated sympatric speciation of indigenous bradyrhizobia isolates. Embu Upper Midland Zone bradyrhizobia isolates had the highest polymorphic loci (80%) and highest genetic diversity estimates (H’ = 0.419) compared to other agro-climatic zones. ConclusionThe high diversity of bradyrhizobia isolates depicts a valuable genetic resource for selecting more effective and competitive strains to improve promiscuous soybean production at a low cost through biological nitrogen fixation.

Response of soil microbial biomass C, N, and P and microbial quotient to agriculture and agricultural abandonment in a meadow steppe of northeast China

The carbon and nutrients in the soil microbial biomass (SMB) and their proportion in soil elements, namely soil microbial quotient (SMQ), are the key indicators of the soil quality and quickly respond to the shift in the land-use pattern. However, the degree of the land-use shift influences on the soil microbial biomass, and the soil microbial quotient in the meadow steppe is not well-understood. The soil microbial biomass carbon (MBC), nitrogen (MBN), phosphorous (MBP), and SMQ were determined separately in grassland, cropland, and abandoned cropland in four sites within 50 km at a meadow steppe in northeast China. The results showed that the soil MBC, MBN, and MBP declined significantly as soil depth increased among the three land-use patterns. Agriculture has resulted in a significant decrease in the soil MBC, MBN, MBP, and SMQ compared to their corresponding values in grassland. The soil MBC content significantly was increased at the 0–10 cm soil layer after agriculture abandonment, but the SMQ had no significant improvement in the entire profile when compared to cropland. Besides, for the three types of land-use patterns, the C, N, and P stoichiometry of the soil microbial biomass was relatively stable, except for the stoichiometry in the relatively deep soil layer. Overall, the present agricultural abandonment (~ 19 years) got a certain of restoration in soil microbial biomass. Their corresponding values, however, were significantly lower than those found in native grassland. This highlighted that the restoration of the poor soil quality caused by the long term agriculture cultivation is a slow and hard process; it is important to maintain natural grasslands for protecting and maintaining soil microbial biomass and SMQ in the meadow steppe of northeast China.

Biochar as a soil amendment in the tree establishment phase: What are the consequences for tree physiology, soil quality and carbon sequestration?

Trees play a pivotal role in the urban environment alleviating the negative impacts of urbanization, and for this reason, local governments have promoted strongly tree planting policies. However, poor soil quality and neglect tree maintenance (e.g., irrigation and fertilization) can seriously mine the plant health status during the tree establishment phase. The use of biochar to provide long-lasting C to the soil and, at the same time, improving soil properties (e.g., improved water holding capacity), soil enzymes activities and NPK concentrations, is a promising research field. Therefore, with a two-step experiment, the study aimed to assay the physiological responses of a commonly used urban tree species (Tilia × europaea L.) to 1.5 % (w/w) biochar amendment (B), and secondly, to assess the ability of trees, grown in biochar amended soil, to tolerate a period of drought. Biochar amendment increased P and K availability in the soil, resulting in higher P and K concentrations in B than control leaves, according to the leaf stage. This induced B trees, higher values in both total biomass than controls (+22 %) in well-watered plants. Moreover, the higher water availability in soil amended with biochar helped B trees to tolerate water stress, with better leaf photosynthetic performances and a faster recovery than stressed controls after the re-watering. This study highlights the dual function of the biochar, improving CO2 sequestration and soil properties, and at the same time, enhancing plant physiological responses to environmental constraints. The use of biochar at the tree planting, especially in an urban environment, is a feasible and environmentally sustainable strategy to improve the success during the tree establishment phase.

Purification and Characterization of Gum-Derived Polysaccharides of Moringa oleifera and Azadirachta indica and Their Applications as Plant Stimulants and Bio-Pesticidal Agents.

Plant gums are bio-organic substances that are derived from the barks of trees. They are biodegradable and non-adverse complex polysaccharides that have been gaining usage in recent years due to a number of advantages they contribute to various applications. In this study, gum was collected from Moringa oleifera and Azadirachta indica trees, then dried and powdered. Characterizations of gum polysaccharides were performed using TLC, GC-MS, NMR, etc., and sugar molecules such as glucose and xylose were found to be present. Effects of the gums on Abelmoschus esculentus growth were observed through root growth, shoot growth, and biomass content. The exposure of the seeds to the plant gums led to bio stimulation in the growth of the plants. Poor quality soil was exposed to the gum polysaccharide, where the polysaccharide was found to improve soil quality, which was observed through soil analysis and SEM analysis of soil porosity and structure. Furthermore, the plant gums were also found to have bio-pesticidal activity against mealybugs, which showed certain interstitial damage evident through histopathological analysis.

The paradox of the supply elasticity of cotton in Mali

ABSTRACT Many previous studies highlight that the supply elasticity of agricultural products is not always symmetric. Indeed, the main finding from the literature is that the supply of agricultural products responds more to rising prices than falling prices. However, in the context of Mali, producers seem to be particularly more sensitive to price falls and prefer to grow other crops such as maize. In this paper, we test whether the supply elasticity of cotton in Mali is asymmetric or not, and if so, characterizes the nature of the asymmetry. We apply a nonlinear Autoregressive Distributed Lag approach to the Nerlove model. Our results show that the supply elasticity of cotton is symmetric in the short-run and asymmetric in the long-run, and that cotton supply responds more to price falls than price rises in the long-run. The key finding is a paradox in the opposite direction of the asymmetry found in the literature. In the context of falling price, producers are more flexible in substituting another competitive crop for cotton, while in the case of rising prices, producers deal with insufficient access to credit and acreage, poor quality of soil and lack of equipment.

Online Monitoring of Ecoenvironmental Pollution Data in Internet Environment

In view of the problems of poor air quality and serious soil pollution in the current ecological environment, an online monitoring of ecological environment pollution data in the Internet environment is proposed. The concentration of pollution sources that may appear in the atmospheric environment is analyzed through the analysis coefficient of ecological environment pollutants, and the specific grade data corresponding to the air quality index is determined. Observation and mapping are carried out for the area to be monitored, and then, the monitoring points are determined, the monitoring equipment is arranged, and the soil profile of the area is sampled in the monitoring area. The self-organizing neural network model is used to conduct spatial cluster analysis on the pollution of ecological environment pollution areas, evaluate the sensitivity of soil pollution, and build a land ecological pollution monitoring information model. Based on the Internet of Things technology and the comprehensive use of GPS, sensors, and other technologies and equipment, the framework of monitoring technology is constructed, and the online monitoring of ecological environment pollution data is completed. The experimental results show that the proposed method has high data accuracy in different locations and different seasons, which is consistent with the actual situation; because of the maturity of the Internet of Things technology, compared with the literature method, the method in this paper can provide a cost-effective data foundation, which is more cost-effective, and save time and energy.