Search Results (7)

In ecological restoration of arid/semi-arid sandy lands, micro-topographic variations and artificial shrub arrangement synergistically drive vegetation recovery and soil quality improvement. As a typical fragile ecosystem in northern China, the Mu Us Sandy Land has long suffered wind erosion, desertification, soil infertility, and vegetation degradation, demanding precise vegetation configuration for ecological rehabilitation. This study analyzed soil nutrients, plant diversity, and their correlations under various micro-topographic conditions across different types of artificial shrub plantations in the Mu Us Sandy Land. Employing one-way and two-way ANOVA, we compared the significant differences in soil nutrients and plant diversity indices among different micro-topographic conditions and shrub species. Additionally, redundancy analysis (RDA) was conducted to explore the direct and indirect relationships between micro-topography, shrub species, soil nutrients, and plant diversity. The results show the following: 1. The interdune depressions have the highest plant diversity and optimal soil nutrients, with relatively suitable pH values; the windward slopes and slope tops, due to severe wind erosion, have poor soil nutrients, high pH values, and the lowest plant diversity. Both micro-topography and vegetation can significantly affect soil nutrients and plant diversity (p < 0.05), and vegetation has a greater impact on soil nutrients. 2. The correlation between surface soil nutrients and plant diversity is the strongest, and the correlation weakens with increasing soil depth; under different micro-topographic conditions, the influence of soil nutrients on plant diversity varies. 3. In sandy land ecological restoration, a “vegetation type + terrain matching” strategy should be implemented, combining the characteristics of micro-topography and the ecological functions of shrubs for precise configuration, such as planting Corethrodendron fruticosum on windward slopes and slope tops to rapidly replenish nutrients, promoting Salix psammophila and mixed plantation in interdune depressions and leeward slopes to accumulate organic matter, and prioritizing Amorpha fruticosa in areas requiring soil pH adjustment. This study provides a scientific basis and management insights for the ecological restoration and vegetation configuration of the Mu Us Sandy Land. Full article

Sandy-textured soil infertility poses a problem for sustainable crop cultivation. This problem is usually dealt with by the addition of chemical fertilizers, which are expensive and can cause serious environmental issues if not managed well. A better alternative to improve and manage sandy soil infertility is the use of organic amendments produced from agro-wastes. This two (2)-year field study was conducted in a sandy-textured soil grown with black pepper to evaluate mainly the effects of chemical fertilizer, fermented plant and fruit juices, compost, and biochar on soil properties and morpho-physiological characteristics and yield of black pepper. Generally, the results indicated that the combination of fermented fruit juice, compost, and biochar was comparable to and in some cases better than chemical fertilizer in terms of soil physical, chemical, and biological properties as well as crop performance. These findings were even more pronounced in the second year of measurements. There were strong positive relationships between soil N and pepper leaf chlorophyll content and between soil microbes and soil respiration. The findings showed that these soil amendments produced from agro-wastes are a good alternative to the use of chemical fertilizers on sandy soils to improve soil fertility and productivity and the yield of black pepper sustainably. Full article

Hairy stork’s-bill (Erodium crassifolium) (HSB) is one of the few Geraniaceae species that produce tubers. While HSB tubers were occasionally used as a food source by desert nomads, they have not yet been taken up in the modern kitchen. Recently, HSB tubers were recognized as harboring potential to become an industrial pharmaceutical crop. The objective of this study was to determine a set of agricultural practices that would maximize the yield of the bioactive compounds of the present HSB genetic material. A generous and consistent irrigation regime of about 700 mm season⁻¹ increased tuber yield and size. The optimal plant density on sandy soils was 16–20 plants m⁻². Mineral nutrition, applied through fertigation, increased tuber yield from 0.6 to almost 1 kg m⁻². Source-sink manipulations (consistent pruning of the reproductive organs) almost doubled the tuber yield. During 10 years of research, the adopted agricultural practices increased yield by an order of magnitude (from about 0.2–2.0 kg m⁻²) without any dilution of the bioactive compounds. Nevertheless, further research and development are required to achieve HSB potential as an industrial field crop, including selection and breeding of outstanding infertile clones, optimization of fertigation, and development of various concrete pharmaceutical products. Full article

The growth of teak (Tectona grandis L. f.) seedlings in sandy soil in northeast Thailand is suppressed by infertility and drought stress. In a preliminary field pot experiment, we confirmed that bentonite was useful for increasing soil water availability. To monitor early growth characteristics of teak seedlings in sandy soil, we curried out an experiment of teak seedlings using bentonite and fertilizer in the field from July 2014 to November 2015. We then compared the growth, biomass, photosynthetic rate, leaf water potential, and concentration of elements in the plant organs among the four treatments. Bentonite increased both soil pH and Ca during the experimental period, and retained P in fertilizer. The dry mass of teak seedlings was markedly increased by concurrent use of bentonite and fertilizer. However, the use of bentonite alone showed little increase of dry mass of teak seedlings. Moreover, application of bentonite was mitigated drought stress in dry season, and photosynthetic rate showed high value by high concentration of chlorophyll. The concentration of K in root of teak seedlings was increased by application of bentonite, and its value showed positive correlation with the relative growth rate of teak seedlings. We concluded that bentonite was useful for the uptake of K and retention of P in fertilizer, as a result, growth of teak seedlings was accelerated. Full article

Productivity and sustainability of tropical forest plantations greatly rely on regulation of ecosystem functioning and nutrient cycling, i.e., the link between plant growth, nutrient availability, and the microbial community structure. So far, these interactions have never been evaluated in the Acacia and Eucalyptus forest planted on infertile soils in the Congolese coastal plains. In the present work, the soil bacterial community has been investigated by metabarcoding of the 16S rRNA bacterial gene in different stands of monoculture and mixed-species plantation to evaluate the potential of nitrogen-fixing trees on nutrient and bacterial structure. At the phylum level, the soil bacterial community was dominated by Actinobacteria, followed by Proteobacteria, Firmicutes, and Acidobacteria. A principal coordinate analysis revealed that bacterial communities from pure Eucalyptus, compared to those from plantations containing Acacia in pure and mixed-species stands, showed different community composition (beta-diversity). Regardless of the large variability of the studied soils, the prevalence of Firmicutes phylum, and lower bacterial richness and phylogenic diversity were reported in stands containing Acacia relative to the pure Eucalyptus. Distance-based redundancy analysis revealed a positive correlation of available phosphorus (P) and carbon/nitrogen (C/N) ratio with bacterial community structure. However, the Spearman correlation test revealed a broad correlation between the relative abundance of bacterial taxa and soil attributes, in particular with sulfur (S) and carbon (C), suggesting the important role of soil bacterial community in nutrient cycling in this type of forest management. Concerning mixed plantations, a shift in bacterial community structure was observed, probably linked to other changes, i.e., improvement in soil fertility (enhanced P and C dynamics in forest floor and soil, and increase in soil N status), and C sequestration in both soil and stand wood biomass with the great potential impact to mitigate climate change. Overall, our findings highlight the role of soil attributes, especially C, S, available P, and C/N ratio at a lesser extent, in driving the soil bacterial community in mixed-species plantations and its potential to improve soil fertility and to sustain Eucalyptus plantations established on the infertile and sandy soils of the Congolese coastal plains. Full article

Most cultivated upland areas of northeast Thailand are characterized by sandy and infertile soils, which are difficult to improve agriculturally. Information about the clay (%) and cation exchange capacity (CEC—cmol(+)/kg) are required. Because it is expensive to analyse these soil properties, electromagnetic (EM) induction instruments are increasingly being used. This is because the measured apparent soil electrical conductivity (EC_a—mS/m), can often be correlated directly with measured topsoil (0–0.3 m), subsurface (0.3–0.6 m) and subsoil (0.6–0.9 m) clay and CEC. In this study, we explore the potential to use this approach and considering a linear regression (LR) between EM38 acquired EC_a in horizontal (EC_ah) and vertical (EC_av) modes of operation and the soil properties at each of these depths. We compare this approach with a universal LR relationship developed between calculated true electrical conductivity (σ—mS/m) and laboratory measured clay and CEC at various depths. We estimate σ by inverting EC_ah and EC_av data, using a quasi-3D inversion algorithm (EM4Soil). The best LR between EC_a and soil properties was between EC_ah and subsoil clay (R² = 0.43) and subsoil CEC (R² = 0.56). We concluded these LR were unsatisfactory to predict clay or CEC at any of the three depths, however. In comparison, we found that a universal LR could be established between σ with clay (R² = 0.65) and CEC (R² = 0.68). The LR model validation was tested using a leave-one-out-cross-validation. The results indicated that the universal LR between σ and clay at any depth was precise (RMSE = 2.17), unbiased (ME = 0.27) with good concordance (Lin’s = 0.78). Similarly, satisfactory results were obtained by the LR between σ and CEC (Lin’s = 0.80). We conclude that in a field where a direct LR relationship between clay or CEC and EC_a cannot be established, can still potentially be mapped by developing a LR between estimates of σ with clay or CEC if they all vary with depth. Full article

When teak (Tectona grandis L. f.) is planted on acrisols in Northeast Thailand, its growth is suppressed by low pH, infertility, and low water holding capacity. To examine materials capable of increasing water holding capacity in soil and improving teak growth, we conducted an experiment with teak seedlings. We selected bentonite, charcoal, and corncob and added these materials at a rate of 4% to sandy soil from northeast Thailand. Teak seedlings were potted on these soils and raised from July 2013 to July 2014. We compared growth, photosynthetic rates, leaf water potential, and concentrations of elements in plant organs among bentonite, charcoal, corncob, and no addition (control) treatments. Water content in the soils was increased for the bentonite and charcoal treatments. Teak seedlings potted in these two conditions did not suffer from drought stress. Comparing the growth traits of the teak seedlings, the charcoal treatment produced larger root growth and promoted the uptake of phosphorus and potassium, whereas the bentonite treatment did not show positive effects on growth or nutrient acquisition. In contrast, the corncob treatment decreased water content in the soil, and teak seedling growth was suppressed. We concluded that charcoal was a useful material to improve teak growth in sandy soils. Full article