Low Soil Nutrient Research Articles

Spatial variations of root-associated bacterial communities of alpine plants in the Qinghai-Tibet Plateau

Exploring the geospatial variation of root-associated microbiomes is critical for understanding plant-microbe-environment interactions and plant environmental adaptability. Root-associated bacterial communities from the three compartments [rhizosphere surrounding soil (RSS), rhizosphere soil (rhizosphere), and root endosphere (endophytic)] are influenced by multiple factors, including plant species and geographical locations. Nonetheless, these communities remain poorly understood under harsh conditions. In this study, we selected four dominant alpine plants on the Qinghai-Tibet Plateau (i.e., Elymus nutans, Festuca sinensis, Kobresia pygmaea, and Kobresia humilis) to investigate their root-associated bacterial communities across 11 geographical locations and determine the factors driving spatial variation. The results showed that the microbiota of the three compartments had significantly different community compositions, with more Pseudomonadaceae and Enterobacteriaceae present in the endosphere. Spatial variations in root endophytic microbiota were mainly governed by stochastic processes, which were different from the deterministic processes in the other two compartments. Meanwhile, the geographical location had greater effects on bacterial communities than plant species, and the spatial variation of α-diversity in the endosphere was much higher than that in the RSS and rhizosphere. We further found that the differentiation of bacterial diversity in the endosphere among sympatric plant species was enhanced by higher annual precipitation, lower soil nutrients (carbon and nitrogen), and pH. For example, the coefficient of variation of endosphere Pseudomonadaceae abundance was positively correlated with annual mean precipitation, whereas that of Enterobacteriaceae abundance was negatively correlated with soil pH. The co-occurrence network analysis identified a higher proportion of bacterial coexistence in the endosphere (70.9%) than in the RSS (49.5%) and rhizosphere soil (50.9%). Finally, we revealed the relative convergence of endophytic communities among sympatric plant species in the alpine grasslands.

Evaluation of nutrient characteristics and bacterial community in agricultural soil groups for sustainable land management.

The soil bacterial community is critical for understanding biological processes in soils and is used for agricultural soil management. The understanding of microorganisms and ecology in different soil groups classified based on soil properties (e.g., minerals, soil texture, location, nitrogen, phosphorus, organic carbon and pH, among others), is limited. To suggest soil management strategies using bacterial data, we classified soils into four groups based on physical–chemical characteristics and elucidated their relationships with soil nutrient characteristics and the bacterial community in agricultural fields in Saraburi Province, Thailand. Results show that soil groups with high bacterial diversity had positive correlations with total Kjeldahl nitrogen and available phosphorus but were negatively affected by total organic carbon and pH levels. Dominant bacterial genera included Lactobacillus, Phascolarctobacterium, Prevotella, Clostridium, Gaiellales and Blautia. Significant key biomarkers were found (p < 0.05). Nutrient-rich soil groups (high available P, acidic pH) were found with genus Agromyces, while low nutrient soil groups (low available P, basic pH) were found with Hydrogenispora, Ignavibacterium and Bauldia. Based on co-occurrence networks, organic degrading bacteria functioned with other bacteria at high degrees of interconnections, suggesting organic amendment, biostimulation and biodegradation using nutrient-rich organic substrates could be used for agricultural soil improvements.

CHARACTERIZATION AND POLYPHASIC IDENTIFICATION OF NOVEL RHIZOBACTERIA STRAIN ISOLATED FROM SAND DUNES ECOSYSTEM

The coastal sand dune ecosystem at the Parangtritis Coast of Yogyakarta, Indonesia has unique characteristics such as low moisture sandy soil, high salinity and low nutrient content. Fimbristylis cymosa is one of the plant species having the capability to survive in that unique ecosystem. In this study, rhizobacteria isolated from the rhizosphere of F. cymosa were isolated to be further analyzed on their phosphate solubilizing and antagonistic properties against Fusarium oxysporum which cause the Wilt disease. The isolates of Phosphate Solubilizing Rhizobacteria (PSR) having the most potential capabilities were then polyphasically identified based on phenotypic and genotypic characters followed by 16S rDNA sequencing. The results showed that four PSR isolates (I8, I11, I12 and I24) have high phosphate dissolution indices. The highest indices were observed in isolates I11 (3.08) and I12 (3.44), respectively. Analysis of the dual plate experiments for PSR I11 and PSR I12 isolates against the growth of F. oxysporum also showed quite high inhibitory activities, i.e., isolate PSR I11 was 42.40%, while isolate PSR I12 was 42.08%. The two isolates were polyphasically identified as Burkholderia dolosa. This study clearly showed that PSR I11 and PSR I12 isolates are very potential and prospective to be used as marginal land inoculants and as providers of phosphorus. This study also showed that the isolates are useful as biocontrol agents against F. oxysporum in plants. Keywords: inhibitory activity, phosphate dissolution index, phosphorus, polyphasic identification, sandy soil

Genotypic variability for tolerance to low soil phosphorus availability in faba bean (Vicia faba L.)

The capacity of legumes to fix atmospheric dinitrogen in partnership with rhizobia provides an input-saving and resource-conserving alternative, thereby reducing the need for chemical fertilizers while enhancing overall crop productivity. However, low soil nutrient availability, notably phosphorus (P), is among the most nutrient limitations for legumes, since legume nodules responsible for N2 fixation have a high P requirement. In order to explore the genetic variability for P uptake and use efficiency in low-P availability in soils, three faba bean genotypes namely Sidi Aich, Castel and Diva were studied in two field sites (S1 and S2) over two growing seasons 2018 and 2019. At flowering stage, plants were harvested and analyzed for their nodulation, growth, P content and yield. Results indicate that low-P availability in the soil of S1 significantly limited plant growth, nodulation, and grain yield for all genotypes though with highest extent for Diva and Castel. We found a significant correlation between nodule growth of all genotypes and Olsen-P content in the rhizosphere soil during two growing seasons. It is concluded that the genotypes selected for their P uptake and use efficiency had a higher yield and could best adapt to low-P availability under field conditions.

Effect of different soilless agriculture methods on irrigation water saving and growth of lettuce (Lactuca sativa)

Environmental stresses such as low soil moisture and soil nutrient deficiency are among the main causes of low crop productivity in arid and semi-arid regions. Soilless cultivation is intensively used in protected agriculture to improve control over the growing environment and avoid uncertainties in the soil's water and nutrient status, leading to better result in water use efficiency, while maintaining the quality of the yield. Therefore, this study was conducted at the Faculty of Agriculture, An Najah University, Palestine, during 2016–17 growing season to investigate the effects of three soilless culture systems compared to agricultural soil growing media on yield and water use efficiency of lettuce crop under greenhouse cultivation. Four different growing media were investigated; pure soil serves as a control, pure volcanic tuff (VT), peat moss perlite mixture (2:1 v/v) and the nutrient film technique (NFT) (hydroponic) and their effect on the growth and productivity of lettuce were monitored. Results showed no significant differences in lettuce crop fresh weight and total fresh weight produced per unit area (m2) within the different growing media tested. In contrast, the different growing media significantly influenced the water use efficiency (WUE) values. Peat moss-perlite mixture and the nutrient film technique (NFT) media resulted in the highest WUE and can save water remarkably, with an irrigated water saved ranging from 94 to 123%, respectively. Overall, results suggest that the NFT hydroponic system is the most efficient system for water-saving and water use efficiency.

Selection of suitable type and application rate of biochar for alfalfa (Medicago sativa L.) productivity in ridge-furrow rainwater-harvesting in semiarid regions of China

Ridge-furrow rainwater-harvesting (RFRH) has emerged as an effective technology to mitigate drought stress, control soil erosion, and increase crop yield in semiarid regions of China. However, the use of plastic film mulch in RFRH makes this technology impractical. A field experiment was conducted for three consecutive years in a randomized complete block design to determine 1) the runoff coefficient for ridges compacted with soil mixed with two types of biochar (rice straw biochar and cow dung biochar) at two application rates (single application rate i.e., 3 × 104 kg ha−1; and double application rate i.e., 6 × 104 kg ha−1; and 2) the effects of the ridges compacted with soil mixed with two types of biochar at two application rates on soil physico-chemical properties, economic benefit, fodder yield and water use efficiency (WUE) of alfalfa, and ridges compacted with soil (no biochar) as control. The average runoff coefficient for NB, SRSB, DRSB, SCDB, and DCDB (NB, SRSB, DRSB, SCDB, and DCDB were ridges compacted with soil, compacted with soil mixed with single rice straw biochar application, double rice straw biochar application, single cow dung biochar application, and double cow dung biochar application, respectively) over these three years was 31%, 28%, 27%, 22%, and 21%, respectively. Ridges compacted with soil-biochar crust had lower runoff coefficients, soil water storage, net income, and higher soil nutrients, when compared to ridges compacted with soil. The topsoil temperature at ridge tops was affected by the ridges compacted with soil-biochar crust, but the topsoil temperature at furrow bottoms was not affected. Compared to ridges compacted with soil mixed with cow dung biochar, ridges compacted with soil mixed with rice straw biochar had lower soil nutrients, and higher soil water storage resulting in higher fodder yield and WUE of alfalfa. With runoff, the nutrients in biochar flowed from ridges to furrows, becoming usable for plants. Ridges compacted with soil-biochar crust increased topsoil nutrients, especially soil organic matter ranging from 15% to 34%, resulting in high fodder yield and WUE of alfalfa. Compared to NB, annual fodder yield for SRSB, DRSB, SCDB, and DCDB increased by 9.0%, 5.9%, 4.4%, and 3.8%, respectively, over three years, while WUE for the same treatments increased by 2.81, 1.95, 0.65, and 0.45 kg ha−1 mm−1. Rice straw biochar at an application rate of 3 × 104 kg ha−1 was found to be suitable type of biochar for increase in fodder yield and WUE of alfalfa in RFRH. Future studies should be conducted in the form of long-term field study to determine economic benefits of biochar application.

Effects of Poultry Manure Application on the Early Seedling Development of Treculia Africana (Breadfruit)

This study was carried out to ascertain the effects of different rates of poultry manure on early seedling development of Treculia africana. The experiment was carried out at Nnamdi Azikwe University Awka. Randomized Complete Block Design was used for the study. A total number of 18 perforated poly bags (48cm×40cm) containing 10kg of soil were laid out in the screen house in a Randomized Completely Block Design (RCBD) with 6 treatments in 3 replicates. The levels of treatment were, 0.0g, 17g, 34g, 51g, 68g, and 85g of poultry manure per 10kg of soil which were sun-dried to conserve the nutrient properties and for easy handling, weighed properly and incorporated into the soil 2 weeks prior to sowing. Growth parameters such as changes in length, girth, leaf area and number of leaves were measured on bi-weekly bases and recorded accordingly. The physicochemical properties of the soil sample and poultry manure is shown in Table 1. The table revealed that the soil sample contained higher composition of sand than silt and clay. The poultry manure contained higher pH, organic carbon, available phosphorus, potassium ion and calcium ion than the soil samples. The effect of different rates of poultry manure on percentage germination of Treculia africana was shown in Table 2. The result of the effect of different rates of poultry manure on the germination of T. africana revealed that rate of 68g/10kg gave the highest percentage germination of (85.17±0.208 %), 85g/10kg gave the highest increase in stem girth from 1.02±0.026cm in week 2. the number of leaves of T. africana indicated that the rate of 85g/10kg gave the highest increase in the number of leaves from 3.50±0.015 in weeks 2 to 5.01±0.010in weeks 8, while 85g/10kggave the highest increase in leaf area from 26.65±2.904cm2 in weeks 2 to 47.80±0.046cm2 in weeks 8. Due to the ecosystem pollutions caused by use of inorganic materials, this study has demonstrated the potential of poultry manure in enhancing the early seedling growth of T. africana in fairly low nutrient soil. There was an increase growth rate of the seedlings with increasing rates of poultry manure. All the parameters of T. africana seedling responded positively to various rate of poultry manure with the seedlings with 85g/10kg rate of the poultry giving the best performance while the control plants gave the lowest performance.

Towards effective reforestation: growth and commercial value of four commonly planted tropical timber species on infertile soils in Panama

Finding suitable tree species that not only grow well on nutrient poor soils but are also safe financial investments is one of the major obstacles to successful reforestation efforts in the tropics. Our study compared the financial viability and growth of valuable timber species in monocultures and mixtures on infertile soils. Our work shows the extraordinary growth in volume and value of Dalbergia retusa and Terminalia amazonia while underscoring the poor financial viability of Tectona grandis and Pachira quinata, all commonly planted timber species in Panama and much of Central and South America. Using Bayesian statistics, our predictions show that T. amazonia monocultures could reach nearly 200 m3 ha−1 of merchantable volume after 30 years compared to the ~ 40 m3 ha−1 that T. grandis could accumulate in the same time frame. While D. retusa monocultures did not have the highest predicted merchantable volumes of all the species, it did have the highest predicted net present value (NPV), with a predicted mean NPV of > US$97,000 ha−1, quadrupling the species with the next highest monoculture’s NPV, T. amazonia monocultures (~ US$20,000 ha−1). Our work emphasizes that reforestation can be financially viable on low nutrient soils, even in the absence of fertilization or other silvicultural manipulations, if species selection and site are carefully considered and matched.

Assessing long-term nutrient and lime enrichment effects on a subtropical South African grassland

Nutrient enrichment influences grassland ecosystem structure, typically manifested by reduced species richness and increased productivity. Quantifying the long-term impacts of nutrient enrichment on grasslands contributes to understanding eutrophication effects on grassland, particularly for grasslands adapted to low soil nutrient status. Overextended time periods, nutrient enrichment may modify soil fertility. The Ukulinga Grassland Nutrient Experiment situated on a natural C4 grassland was set up in 1951 on the Ukulinga research farm, South Africa. Continuously applied treatments on plots measuring 2.7 × 9 m include combinations of nitrogen at 0, 7, 14 and 21 g m−2 per annum, phosphorus at 0 and 2.8 g m−2 per annum and lime at 0 and 225 g m−2 applied every five years. Nitrogen sources included ammonium sulphate (acidifying) and limestone ammonium nitrate (less acidifying). Grass species composition was influenced by both nitrogen forms. In contrast, forb species composition was more sensitive to LAN. We found evidence of nitrogen limitation on aboveground net-primary production. However, species richness (for grass and forbs) declined with increasing ammonium sulphate levels, owing to increased soil acidity and high aluminium concentrations. Aluminium toxicity can affect overall species composition by replacing Al-sensitive species with Al-tolerant species on site.

PENINGKATAN PERTUMBUHAN, SERAPAN UNSUR HARA N, P, K SERTA PRODUKSI TANAMAN JAGUNG DI ENTISOL KALIDAWIR, TULUNGAGUNG AKIBAT APLIKASI PUPUK KANDANG SAPI DAN PUPUK NPK

Entisols are newly formed soil types and are commonly found in Indonesia, with a distribution of ±3 million ha distribution. Entisol Kalidawir has a slightly acidic pH value of 5.8 and contains very low total-nitrogen (N) and available-phosphorus (P) nutrients, calcium (Ca), sodium (Na) and magnesium (Mg) in the exchangeable base are also low and clay loam texture. Low soil nutrients and organic matter can have an impact on plant growth and production Maize is one of the most widely cultivated food crops in Indonesia. The purpose of this study was to analyze various doses of the combination of cow manure and NPK fertilizer on N, P and potassium (K) uptake, growth and production of maize. The results showed that the application of 20 t ha-1 of cow manure and 400 kg ha-1 of NPK fertilizer at observations 27 and 54 days after planting increased growth in height and number of leaves of corn plants and increased nutrient uptake of N, P, and K, respectively. Also reached 1, 0.14, and 0.82 g plant-1 and 5.52, 0.83, and 5.11 g plant-1. In addition, it produces the highest corn production of 10.53 t ha-1.

Seedball technology enhances pearl millet yield in a Sahelian subsistence production system

Pearl millet (Pennisetum glaucum (L.) R.Br.) is the major staple crop produced by subsistence farmers in the West African Sahel, but its panicle yield is low because of poor seedling establishment in low-nutrient soils. Seedball is a cheap seed-pelleting technique that combines sand, loam, seeds and optionally wood ash or mineral fertiliser as an additive to enhance early growth of pearl millet under infertile soil conditions. The aim of this study was to investigate the effects of seedball technology on pearl millet crop establishment and panicle yield on-farm under Sahelian subsistence conditions. Over 2000 on-farm (2015–18) trials were conducted in 65 villages of the Maradi region in Niger. Conventionally sown and seedball-derived pearl millet crops were grown by using ‘farmer-optimised’ simple split-plot designs with three treatments: (i) farmers’ practice as control; and seedballs (2.0 cm diameter, made from 80 g sand + 50 g loam + 25 mL water + 2.5 g seeds as standard recipe) that contained either (ii) 3 g wood ash or (iii) 1 g mineral fertiliser (nitrogen, phosphorus, potassium; NPK) as effective nutrient compounds. In 2016–18, participating farmers could opt for one of the seedball treatments. Panicle as well as stover yield data were collected and compared with respect to seedball type (wood ash vs NPK), sowing depth (shallow vs deep), sowing time (wet vs dry), weed management (complete vs partial), local soil type (texture range sand to loamy sand), cropping system (sole vs mixed), and farmer. Results showed that seedballs do not suppress seedling emergence. Seedball treatments produced fewer but longer and denser panicles. Wood ash-amended seedballs showed a higher panicle yield increase relative to their site controls than NPK-amended seedballs. However, the average panicle yield of NPK-amended seedballs was higher than that of the wood ash-amended seedballs. The treatment factors wet sowing, partial weeding, sole cropping and farmers showed higher panicle yield. The seedball technology increases pearl millet panicle yield by ∼30% in the Sahel; it is simple and based on local materials.

Soil nutritional status in KwaZulu-Natal drives symbiotic interactions and plant performance in

Context Cancer bush (Lessertia frutescens L.) is a multipurpose medicinal legume endemic to southern Africa, reported to grow in a variety of soils, from very poor to fertile ones. However, there is limited knowledge on how L. frutescens is able to thrive in diverse soils and, particularly, nothing has been reported on the benefits from the microbe symbiosis, plant growth and acclimation to low nutrient soils. Aims Therefore, this study examined the effect of soil nutrient deficiency in plant–microbe symbiosis, nitrogen (N) nutrition and associated plant performance of L. frutescens plants, growing in four different impoverished soils from the KwaZulu-Natal region. Methods Experimental soil samples collected from four geographical distinct KwaZulu-Natal (KZN) locations (Hluhluwe, Izingolweni, Bergville and Ashburton) representing grasslands and savanna were used as natural inoculum and growth substrate. Key results Soil analysis showed significant differences in soil pH, exchange acidity, total cations, organic carbon (C), phosphorus (P) and N related to differences in the soil provenance. L. frutescens root nodules were dominated by Bacillus sp. in all soil treatments, except in plants grown in Bergville soil that did not nodulate. In all, 68–90% of total plant N concentration was reduced from atmospheric N. L. frutescens plants also relied on soil-available N for growth. Hluhluwe and Ashburton soil-grown plants showed a significantly higher biomass than did other soil-grown plants. Conclusions These current findings demonstrated that L. frutescens root nodules were dominated by bacteria characterised as phospho-bacteria and N2-fixing bacteria in these impoverished soils. This enabled L. frutescens to fix atmospheric N and assimilate soil available N to reduce energy demand. Implications These strategies may collectively contribute to L. frutescens resilience in nutrient-deficient savanna and grassland ecosystems.

Assessment of the impacts of toposequence on soil properties and quality in Tula, Gombe State, Nigeria

Abstract Soil erosion and a decline in fertility are influenced by insidious topography, which results in the problem of food insecurity in developing countries. Tula is a slope terrain, thus, prone to soil degradation due to continuous cultivation, hence the need to assess soil variability and quality to guide on suitable management practices to adopt across the slope classes. Hence, this study was conceived to assess the effect of toposequence on soil properties and quality in Tula, Gombe state Nigeria. Three slope classes were selected (upper, middle and lower slope). Soil samples were collected from each slope class at depths of 0–15 cm and 15–30 cm and analysed for soil physical and chemical properties using standard procedures. The results show that the soil texture varies from loamy sandy to sandy. The bulk density ranges from 1.02 to 1.12 mg.cm−3 and were rated medium at &lt;1.6 mg.cm−3. Soils on the lower slope were significantly (p &lt; 0.05) higher in soil pH. The soils were generally slightly acidic to neutral. Soil organic carbon was medium in the upper and lower slopes (&gt;10 mg.kg−1), while the middle slope was low. The exchangeable bases were rated medium to high across the slope. The soils in the upper slope were of high quality (17 = SQ1), soils in the lower slope were moderate in quality (22 = SQ2) due to low effective cation exchange capacity, and soils in the middle slope were poor in quality (26 = SQ3) due to low soil nutrients. The implication to farmers is that crop grown on upper and lower slope will grow better than those on middle slope due to variations in nutrients. The middle slope was more afflicted by denudation processes because its steep slopes favour erosion. In conclusion, our data show that soil nutrient and quality varies across slope classes and different management practices should be adopted based on slope classes for sustainable crop production. Farmers are therefore advised to add more organic manure and crop residues as well as practice terrace farming on the middle slope for sustainability.

Planted forests intensified soil microbial metabolic nitrogen and phosphorus limitation on the Loess Plateau, China

Appropriate plantation density is conducive to sustainable forest development. It is no consistent conclusion on how the construction of plantations, especially stand density, may affect soil enzymes activities and stoichiometry. The surface soil (0–20 cm) was sampled from Pinus tabuliformis plantations with low- (725–875 stem·hm−2), medium- (1375–1500 stem·hm−2), and high- (2150–2200 stem·hm−2) stand density and natural P. tabuliformis forests with medium- (1250–1400 stem·hm−2) and high- (2000–2700 stem·hm−2) stand density on the Loess Plateau in China. We measured the activities of C-, N-, and P-degrading enzymes (β-1,4-glucosidase, BG; β-1,4-N-acetylglucosaminidase, NAG; leucine aminopeptidase, LAP; and alkaline phosphatase, AP) and other major environment factors (i.e., vegetation characteristics, soil physicochemical properties, and microbial biomass). We found that (1) the activities of soil C- (BG), N- (NAG + LAP), and P- (AP) degrading enzymes were significantly higher in plantations than in natural forests owing to the lower soil nutrients content. (2) The soil enzyme stoichiometry ratio (C:N:P) of the natural forests and plantations deviated from the global average. Furthermore, the C:N and C:P ratios significantly decreased due to the significant increase of N- and P- degrading enzymes activities in medium- and high-density plantations. (3) Vector analysis showed that soil microbes were limited by C and N in natural forests. On the other hand, afforestation alleviated microbial C limitation, intensified N limitation, and caused P limitation. (4) The RDA analysis showed that soil enzymes activities and stoichiometry were mainly affected by soil organic C, available P, and microbial biomass C. Low-density P. tabuliformis plantations are conducive to improving ecological forest structure and plant diversity and may reduce soil microbial N and P limitation.

Synergy of saprotrophs with mycorrhiza for litter decomposition and hotspot formation depends on nutrient availability in the rhizosphere

Plants acquire and recycle nutrients from soil organic matter, and these dynamics depend on a highly diverse array of microorganisms in the rhizosphere. Although functions of many microbial groups have been identified, how different groups interact to affect biogeochemical processes is still poorly understood. We investigated the interactive effects of saprotrophs and arbuscular mycorrhizal fungi (AMF) on Medicago sativa litter decomposition and spatial distribution of enzyme activity in the rhizosphere in nutrient poor and rich soils, using compartmented microcosms designed for zymography. In nutrient poor soils, co-inoculation of saprotrophic bacteria (Alcaligenes faecalis) or fungi (Phanerochaete chrysosporium) with AMF (Rhizophagus irregularis) resulted in faster litter decomposition and greater hotspot areas of enzymes in the rhizosphere compared to mono-inoculations. These positive effects were stronger in the interaction of AMF with saprotrophic bacteria than that with saprotrophic fungi. The synergy of saprotrophic bacteria with AMF for litter decomposition and enzymatic hotspot formation was weaker in nutrient rich soils than that in nutrient poor soils. In contrast, in nutrient rich soils, co-inoculation of saprotrophic fungi with AMF reduced litter decomposition. A partial least squares path modeling (PLS-PM) analysis indicated that faster litter decomposition and larger enzymatic hotspots increased overall plant growth. These findings suggest the existence of important synergistic relationships between these two microbial guilds for plant growth in nutrient poor soils. Specifically, AMF accelerated litter mineralization by increasing saprotrophic biomass and enzyme activities (i.e., nitrate reductase, urease and cellulase). At the same time, saprotrophs increased AMF colonization rate, which increased the hotspot areas of enzyme activities. These hotspots, in turn, broadened the nutrient mobilization zone around the roots - in the rhizosphere. Consequently, the synergistic interactions between saprotrophs and AMF for litter decomposition and the formation of enzymatic hotspots may be an important mechanism for promoting plant fitness under low soil nutrient availability.

Complementary effect of zoo compost with mineral nitrogen fertilisation increases wheat yield and nutrition in a low-nutrient soil

Excess nitrogen (N) fertiliser use in agriculture is associated with water pollution and greenhouse gas emissions. While practices and programs to reduce N fertiliser application continue to be developed, inefficient fertiliser use persists. Practices that reduce mineral N fertiliser application are needed in a sustainable agricultural ecosystem to control leaching and gaseous losses for environmental management. This study evaluated whether fully or partially replacing mineral N fertiliser with zoo compost (Perth Zoo) could be a good mitigation strategy to reduce mineral N fertiliser application without affecting wheat yield and nutrition. To achieve this, a glasshouse experiment was conducted to assess the complementary effect of zoo compost and mineral N fertiliser on wheat yield and nutrition in a sandy soil of southwestern Australia. Additionally, a chlorophyll meter was used to determine whether there was a correlation between chlorophyll content and soil mineral N content, grain N uptake, and grain protein content at the tillering (42 d after sowing (DAS)) and heading (63 DAS) growth stages. The standard practice for N application for this soil type in this area, 100 kg ha -1 , was used with a soil bulk density of 1.3 g cm -3 to calculate the amount of mineral N (urea, 46% N) and Perth Zoo compost (ZC) (0.69% N) for each treatment. Treatments comprised a control (no nutrients added, T1), mineral N only (100 kg N ha -1 , T2), ZC only (100 kg N ha -1 , T7), and combinations of mineral N and ZC at different rates (mineral N at 100 kg N ha -1 + ZC at 25 kg N ha -1 (T3), mineral N at 75 kg N ha -1 + ZC at 25 kg N ha -1 (T4), mineral N at 75 kg N ha -1 + ZC at 50 kg N ha -1 (T5), and mineral N at 50 kg N ha -1 + ZC at 50 kg N ha -1 (T6)). The T6 treatment significantly increased grain yield (by 26%) relative to the T2 treatment. However, the T7 treatment did not affect grain yield when compared to the T2 treatment. All treatments with mineral N and ZC in combination significantly improved the 1 000-grain weight compared to the T2 treatment. Chlorophyll content was better correlated with soil mineral N content ( r = 0.61), grain N uptake ( r = 0.62), and grain protein content ( r = 0.80) at heading (63 DAS) than at tillering (42 DAS). While ZC alone could not serve as an alternative to mineral N fertiliser, its complementary use could reduce the mineral N fertiliser requirement by up to 50% for wheat without compromising grain yield, which needs to be verified in the field. Chlorophyll content could be used to predict soil mineral N at the heading stage, and further studies are warranted to verify its accuracy in the field. Overall, the application of ZC as part of integrated nutrient management improved crop yield with reduced N fertiliser application.

Effect of Brick kilns emissions on land, water, agriculture production, socio-economic and livelihood status: A Review

Rapid growth in population leads to urbanization resulting in considerable land use, land covers changes, and creates a sequence of environmental and food security problems. Due to speedy urbanization the agricultural lands has been converted into no-agricultural activity such as brick production. Brick kilns required larger areas for brick production and it removes agriculturally productive topsoil rich in clay, soil organic matter content and others important soil nutrient that is viable for agricultural growth. In addition to the removal of fertile top soil, brick kilns making process also emits harmful gases into the atmosphere. This harmful gaseous emission from brick kilns impacts the available natural resources and livelihood nearby it. Its emission results in decreased land and plant productivity, lowered ground water levels, and particularly leads to air pollution. It was found that neighbouring areas of brick kilns has low organic matter content and soil nutrients, and high soil electrical conductivity and low pH. It also changes the chemical and biological characteristics of soil and water. A change in physical, chemical and biological parameters of soil and water leads to reduce cultivated areas, and finally reduces agricultural production and productivity. It also directly impacts the food production system and could threaten the livelihood of present and future generations by degrading agricultural soil and consequently also eroding the economic basis of farmers.

Using demographic findings to compare wild and translocated populations of Florida goldenaster (Chrysopsis floridana) in west‐central Florida, U.S.A.

Evaluation of the success of rare plant introductions requires analysis of demographic success. We analyze the success of 10 wild and 8 introduced populations of Florida goldenaster (Chrysopsis floridana), a federally endangered forb endemic to west‐central Florida, using demographic and stage‐class data collected from 2017 to 2019. We also collected microhabitat data to characterize factors associated with this species' success. Introductions had higher annual survival rates and fecundity than wild populations; plants in scrub plots had higher survival than roadside plants, although fecundity was higher in roadside plants. Seedling recruitment was only higher for scrub plots in 1 year. Chrysopsis floridana occupancy was better predicted by lower soil nutrients and pH, but introduction success did not consistently vary according to soil conditions. Occupied plots had higher cover of bare sand, lichens, and forbs while unoccupied plots had higher cover of litter, shrub, and subcanopy. The presence of higher litter levels (&gt;60%) appeared to significantly lower survival in 2018. Z‐score site ranking suggested a slight disadvantage for wild populations overall, with the two highest ranked sites both being introductions. Conversely, stage‐class data revealed that both wild and introduced populations had high counts across 3 years of sampling. Most of the healthiest populations had received recent fire, suggesting this may be crucial in providing conditions that promote recruitment and occupancy. More information is needed on aspects of fire and fire surrogates that are likely to affect the demography and distribution of this rare species.

Biological Flora of the British Isles: Salvia pratensis

Abstract This account presents information on all aspects of the biology of Salvia pratensis L. (Meadow Clary) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. Salvia pratensis is an erect, rosette‐forming, perennial herb with a broad native distribution covering much of Europe—from the British Isles, Spain and Morocco in the west, across Europe into Asia, as far east as the Urals. In the British Isles, the species is nationally scarce, confined to a few south‐ to west‐facing sites with calcareous soils in Southern England and one site in Wales. It is predominately found in unimproved pasture, hay meadows and grassy verges, but can occur on the fringes of scrub or woodland. Although the species is abundant in central Europe, changes to land management since the mid‐20th century have resulted in fragmented and threatened populations in several European countries. It is cultivated as an ornamental, as is S. × sylvestris, the hybrid with S. nemorosa. Populations are typically gynodioecious, having both female (male‐sterile) and hermaphrodite individuals at variable proportions. The species has a mixed mating system and is self‐compatible via insect pollination, but predominantly outcrosses. Honeybees and bumblebees are abundant pollinators, but a diverse range of bee species and other insect species visit S. pratensis flowers. Inbreeding depression has been documented, presenting a conservation concern for small, fragmented populations. The species is the focus of conservation efforts and has been reintroduced to sites where it had become locally extinct in Britain. To sustain favourable habitat, site management should maintain low soil nutrient levels, and prevent scrub encroachment and the dominance of coarse grasses. The removal of sward by hay cutting or grazing after plants have flowered and set seed is advised, in addition to maintaining a degree of disturbance to provide bare patches of soil for seedling recruitment.

Ecophysiological responses of Terminalia sericea to fire history in a semi-arid woodland savanna, central Namibia

Woody vegetation is increasing in savanna ecosystems worldwide. Fire is frequently used as a management tool to decrease bush encroachment, but knowledge regarding the underlying leaf-level ecophysiological responses to fire history is lacking. In southern Africa, Terminalia sericea is a dominant encroaching species that resprouts readily following fires. The impact of fire on leaf-level photosynthesis, transpiration, conductance and water use efficiency was investigated using infrared gas analysis. Data were collected in three areas on the Waterberg Plateau with different fire histories (fire occurring 2, 3 and 15 years prior to sampling). Leaf-level photosynthetic rates were comparable to the relatively high rates shown by other encroaching bush species. In contrast to expectations, ecophysiological variables did not differ among plants in areas with different fire histories. However, photosynthetic rates were highly sensitive to variation in light level, suggesting that canopy structural differences may affect carbon fixation and growth rates at the whole-plant level. Encroachment by T. sericea may be facilitated, at least in part, by high leaf-level photosynthetic rates that are insensitive to long-term fire history on sandy, low-nutrient soils.