Nutrient-poor Soils Research Articles

Prey exclusion combined with simulated fire increases subsequent prey-capture potential in the pale pitcher plant, Sarracenia alata.

The association of carnivory (an adaptation to nutrient-poor soils) with fire has been described as a paradox, given increases in nutrient availability that often accompany fire. The nutrients that increase in availability following fire, however, may not be the same as those provided by prey and may not reduce nutrient limitation if accompanied by even greater increases in light. Using a factorial experiment in the field, we examined how simulated fire (clipping plus nitrogen-free fertilizer addition) and prey-derived nutrient availability (prey exclusion) interacted to influence carnivorous potential in Sarracenia alata and belowground competition with its neighbors (manipulated via trenching). We hypothesized that simulated fire combined with prey exclusion would (1) increase the potential for prey capture relative to shade avoidance, hereafter, relative prey-capture potential (RPCP), and/or (2) increase belowground competition with neighboring plants. Sarracenia alata increased RPCP in response to the combination of simulated fire and prey exclusion, despite increases in phosphorus and other nutrients associated with the simulated fire treatment, suggesting that prey capture potential increases in response to increased nitrogen limitation resulting from increases in light and/or phosphorus after fire. We found no evidence of belowground competition. The potential importance of carnivory in Sarracenia alata increases following fire. This result helps to explain the paradoxical association of carnivorous plants with fire by demonstrating the potential for prey-derived nutrient limitation to increase rather than decrease in response to increases in light and nutrients other than nitrogen following fire.

Soil nutrient variation along a shallow catena in Paracou, French Guiana

Tropical forests are generally considered to stand upon nutrient-poor soils, but soil nutrient concentrations and availabilities can vary greatly at local scale due to topographic effects on erosion and water drainage. In this study we physically and chemically characterised the soils of 12 study plots situated along a catena with a shallow slope in a tropical rainforest in French Guiana both during the wet and the dry season to evaluate seasonal differences. Soils along the catena were all Acrisols, but differed strongly in their water drainage flux. Over time, this differential drainage has led to differences in soil texture and mineral composition, affecting the adsorption of various nutrients, most importantly phosphorus. The more clayey soils situated on the slope of the catena had higher total concentrations of carbon, nitrogen, phosphorus and several micronutrients, while extractable nutrient concentrations were highest in the sandiest soils situated at the bottom of the catena. We found that carbon, nitrogen and extractable nutrients all varied seasonally, especially in the surface soil layer. These results are interesting because they show that, even at the local scale, small differences in topography can lead to large heterogeneity in nutrient concentrations, which can have large impacts on plant and microbial community organisation at the landscape level.

Nitrifying Microbes in the Rhizosphere of Perennial Grasses are Modified by Biological Nitrification Inhibition.

Soil nitrification (microbial oxidation of ammonium to nitrate) can lead to nitrogen leaching and environmental pollution. A number of plant species are able to suppress soil nitrifiers by exuding inhibitors from roots, a process called biological nitrification inhibition (BNI). However, the BNI activity of perennial grasses in the nutrient-poor soils of Australia and the effects of BNI activity on nitrifying microbes in the rhizosphere microbiome have not been well studied. Here we evaluated the BNI capacity of bermudagrass (Cynodon dactylon L.), St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze), saltwater couch (Sporobolus virginicus), seashore paspalum (Paspalum vaginatum Swartz.), and kikuyu grass (Pennisetum clandestinum) compared with the known positive control, koronivia grass (Brachiaria humidicola). The microbial communities were analysed by sequencing 16S rRNA genes. St. Augustinegrass and bermudagrass showed high BNI activity, about 80 to 90% of koronivia grass. All the three grasses with stronger BNI capacities suppressed the populations of Nitrospira in the rhizosphere, a bacteria genus with a nitrite-oxidizing function, but not all of the potential ammonia-oxidizing archaea. The rhizosphere of saltwater couch and seashore paspalum exerted a weak recruitment effect on the soil microbiome. Our results demonstrate that BNI activity of perennial grasses played a vital role in modulating nitrification-associated microbial populations.

Response of C, N, and P stoichiometry characteristics of Broussonetia papyrifera to altitude gradients and soil nutrients in the karst rocky ecosystem, SW China

The ecological stoichiometry of forest ecosystem has rapidly increased in recent years, but studies on C, N, P stoichiometric characteristics of plant fine root-leaf-litter-soil continuum are very weak and the coupling relationships between underground and aboveground ecosystems are urgently to be studied, especially in the kart rocky desertification ecosystem of Southwest China. The aims of the present study is to clarify the response of C, N, and P stoichiometric characteristics of Broussonetia papyrifera to altitude gradients and soil nutrients in the karst rocky ecosystem and conclude the adaptative strategies of B. papyrifera to the karst rocky desertification environments. Six sampling zones of B. papyrifera were set between the altitude gradient of 500–1100 m in the study area for random sampling. The organic carbon (C), total nitrogen (N), and total phosphorus (P) contents of B. papyrifera fine root, leaf, litter, and rhizosphere soil were determined, respectively. Data were analyzed statistically by linear regression, Pearson correlation analysis, LSD multiple comparison and principal component analysis. There are significant positive correlations between N and P contents in fine root, litter, and rhizosphere soil. The nutrient contents and ratios of fine root and litter were the key indexes to evaluate the stoichiometric characteristics of B. papyrifera continuum. Altitude can significantly influence on nutrient contents and stoichiometric ratios of B. papyrifera fine root, leaf, litter and soil. N resorption efficiency of B. papyrifera decreased significantly when altitude increased, and the P resorption efficiency of high altitude plants was lower than that of low altitude plants. Moreover, there were significant correlations between nutrient contents and ratios in B. papyrifera fine root, leaf, litter and rhizosphere soil. The B. papyrifera growth in the karst rocky desertification ecosystem of Southwest China was mainly restricted by P element. Rhizosphere soil P content was the most significant factor in the leading to the change of stoichiometric characteristics of B. papyrifera fine root and leaf. There were obvious responses of C, N and P stoichiometric characteristics in B. papyrifera leaf – fine root – litter – rhizosphere soil continuum to altitudinal gradients. B. papyrifera had good adaption strategies to the poor soil nutrient and high altitudinal environments in the karst rocky desertification ecosystem.

Fencing enclosure alters nitrogen distribution patterns and tradeoff strategies in an alpine meadow on the Qinghai-Tibetan Plateau

The grasslands of Qinghai-Tibetan Plateau have become extremely degraded, resulting in widespread deficiency of soil N. In efforts to restore degraded lands, fencing enclosure has been used extensively. However, the effect of fencing on N allocation patterns and nutritional strategy of alpine plants are equivocal. In this study, we used 15N tracer (CO (15NH2)2, 10 g N m−2) to examine the allocation and distribution of N in plants and soil in grasslands either grazed heavily by livestock or fenced for three years in an alpine meadow of Northern Tibet. The 15N recovery (15Nrec) in shoots of the fenced enclosure increased by 207% in grasses, decreased by 103% in forbs, and did not change in sedges when compared to the grazed meadow. The 15Nrec in shoots accounted for only 1.97% and 4.65% of the total N in the grazed and fenced meadows, respectively. Fencing increased soil 15N content at 0–5 cm depth by 6.9%, but decreased the content at 5–10 cm depth by 11.7%. The results demonstrated that fencing altered the soil N distribution by increasing 15Nrec in top soil and by decreasing 15Nrec in subsurface soil. In addition, fencing had no impact on root 15N storage (33%–39%), 15N losses (9.6%–12.5%) and soil available 15Nrec (NH4+-N, NO3–-N and light fraction organic N), but decreased root:shoot 15Nrec ratio by 49.8% (16.9:1 in grazed and 8.4:1 in fenced grassland). Fencing increased soil organic carbon, total N and NO3–-N concentrations, which indicated that the strategy of the plants was to allocate relatively more N to roots in nutrient-poor soil (grazed) but relatively more N to shoots in nutrient-rich soil (fenced).

Effect of biochar and compost application on nitrogen dynamics in organically managed nutrient-poor paddy soil system and in organic rice cultivation system

Nitrogen (N) is an essential plant nutrient, and its retention in the soil is beneficial to plant growth and productivity. High levels of N can leach from soil with organic amendments, particularly in water-rich paddy rice cultivation. Biochar has the potential to influence the soil N cycle. The study included four treatments applied to organically managed nutrient-poor paddy soil (S) and rice cultivation (R) systems, respectively over two growing seasons: biochar only (BA), compost only (CA), biochar and compost mixed at an equal rate (BC), and no amendment (control). Biochar produced from mangrove (Rhizophora apiculata) which obtained from slow pyrolysis in a traditional kiln, whereas compost generated from organic municipal solid waste. The results showed that, on average, BA and BC maintained NO3--N and NH4+-N in the soil and reduced absolute N leaching compared to the control and CA, respectively. System R maintained nitrogen better than system S. BA reduced N mass leaching by 27.25% in system S and by 59.21% in system R, compared to the control, while BC reduced N mass leaching by 24.85% in system S and by 58.48% in system R, compared to CA. However, the reduction in N2O emission fluxes was not significant in both BA and BC in both seasons, although cumulative emission fluxes after a year of cultivation decreased significantly. BC significantly boosted water use efficiency relative to yield in system R. These results show that co-application of biochar and compost to nutrient-poor soil in an organically managed system substantially reduced N leaching and suggests that it could be an effective management option for organic rice cultivation in Thailand. Keywords: Biochar, compost, nitrogen leaching, N2O emmision, nitrogen balance, organic rice cultivation.

Changes in Chemical and Microbial Soil Parameters Following 8 Years of Deadwood Decay: An Experiment with Logs of 13 Tree Species in 30 Forests

Deadwood may alter the chemical and microbial properties of forest soils. However, it is unclear how downed deadwood (logs) of different tree species affect nutrients, microbial activity and biomass in different forest soils and regions. We investigated the effect of logs on underlying soils after 8 years of decomposition in an experiment consisting of 13 log tree species replicated at 30 forest sites across three German regions with distinct climate and geology. Soils beneath logs were compared to soils without recognizable influence of deadwood (control) 8 m away. Carbon, nitrogen, phosphorous and calcium concentrations increased by 5–18% in the soils under logs, whereas soil potassium, magnesium, iron, manganese and aluminum were not or slightly negatively affected by logs. Soils beneath logs exhibited 33%, 18% and 54% higher carbon mineralization, microbial biomass and ergosterol (component of fungal cell membranes) contents, respectively. Despite major differences in decay rates, the effect on soil properties hardly differed among the 13 log tree species. The effect of logs on microbial and chemical soil parameters increased with decreasing concentration of carbon, nitrogen, phosphorous and pH in the prevailing forest soils. Consequently, the strongest effects of logs on soil parameters occurred in plots with low soil nutrient contents and low soil pH. Our results suggest that logs of all tree species primarily increase the microbial activity and nutrient contents of acidic and nutrient-poor soils.

Draft Genome Sequence of Collimonas pratensis Strain PMB3(1), an Effective Mineral-Weathering and Chitin-Hydrolyzing Bacterial Strain

We announce the draft genome sequence of Collimonas pratensis PMB3(1), isolated from the Scleroderma citrinum mycorrhizosphere. In addition to its mineral-weathering effectiveness and antifungal activity, this strain is characterized by genomic features that give it great potential as a biocontrol and plant growth-promoting agent in nutrient-poor soils.

Dual transcriptomics and proteomics analyses of the early stage of interaction between Caballeronia mineralivorans PML1(12) and mineral.

Minerals and rocks represent essential reservoirs of nutritive elements for the long-lasting functioning of forest ecosystems developed on nutrient-poor soils. While the presence of effective mineral weathering bacteria was evidenced in the rhizosphere of different plants, the molecular mechanisms involved remain uncharacterized. To fill this gap, we combined transcriptomic, proteomics, geo-chemical and physiological analyses to decipher the potential molecular mechanisms explaining the mineral weathering effectiveness of strain PML1(12) of Caballeronia mineralivorans. Considering the early-stage of the interaction between mineral and bacteria, we identified the genes and proteins differentially expressed when: (i) the environment is depleted of certain essential nutrients (i.e., Mg and Fe), (ii) a mineral is added and (iii) the carbon source (i.e., glucose vs mannitol) differs. The integration of these data demonstrates that strain PML1(12) is capable of (i) mobilizing iron through the production of a non-ribosomal peptide synthetase-independent siderophore, (ii) inducing chemotaxis and motility in response to nutrient availability and (iii) strongly acidifying its environment in the presence of glucose using a suite of GMC oxidoreductases to weather mineral. These results provide new insights into the molecular mechanisms involved in mineral weathering and their regulation and highlight the complex sequence of events triggered by bacteria to weather minerals.

Contrasting effects of land tenure on degradation of Cambisols and Luvisols: The case of Central Bohemia Region in the Czech Republic

Identifying key drivers of land degradation is essential to mitigate or prevent land degradation, promote land recovery, and achieve improvement at national and international levels. The aim of this study was to test whether the level of land tenure security affects the degree of soil degradation. The level of land tenure security was tested on two contrasting soil types to determine whether the initial soil quality may mitigate the effect of poor management. The following soil degradation indices were selected: soil compaction, soil organic matter content (SOM), and soil aggregate stability, measured as mean weight diameter (MWD), and weight of each size fraction. The soils tested belonged to one of the two soil types: Cambisol (with a sandy loam texture) or Luvisol (with a silt loam texture). Luvisols had higher SOM, macro aggregates, and compaction levels compared with Cambisols. In addition, Luvisols were not related to tenure security. Based on the results, Cambisols were affected by tenure security, and owner-managed soils had the highest SOM content and the lowest soil compaction. In addition, the Cambisols managed by long-term tenants were less compacted than soils managed by short-term tenants, because SOM is a long-term indicator. Therefore, a management practice that has been implemented for less than 10 years will not have a significant impact on this indicator. Owner-operators are likely to retain the soil for a longer period of time than either of the two groups of tenant farmers. Thereby, they would be able to affect the long-term characteristics of the soil better than the tenants. There was no significant difference in the mean weight of the soil aggregates between differently managed soils. This study concluded that the willingness of a farmer to invest in the soil is affected by tenure security and the length of the contract, which may be reflected by the soil quality, especially in nutrient-poor soils.

Does defoliation frequency and severity influence plant productivity? The role of grazing management and soil nutrients

Rangeland management approaches, including rotational grazing, rely on assumptions about plant growth responses to the intensity, or severity (sward height) plus frequency, of defoliation. We tested these assumptions at the farm, patch and plant scale using data from a grazing management trial in an Eastern Cape mesic grassland of South Africa along with field plot and glasshouse pot experiments. The grazing trial tested season-long grazing (SLG), four-camp grazing (FCG) and holistic planned grazing (HPG) at equivalent stocking rates over three years. We found that grass growth responses in both potted plants and field plots were reduced under more frequent and severe defoliation but that this was mitigated under elevated soil nutrients, in line with the Compensatory Continuum Hypothesis which predicts that compensatory growth will increase across an increasing fertility gradient. In the farm trial, SLG, which theoretically causes high frequency, low severity defoliation, reduced bare ground cover and increased vegetation greenness with increasing defoliation intensity on nutrient-rich soils. This effect was not present under FCG or HPG and disappeared under very high defoliation intensities and on relatively water- and nutrient-poor soils. Managers are advised to only increase grazing frequency on relatively high nutrient soils, while maximizing recovery on poorer nutrient soils.

Saline-alkali soil applied with vermicompost and humic acid fertilizer improved macroaggregate microstructure to enhance salt leaching and inhibit nitrogen losses

High salinity, poor soil structure and nutrient deficiencies are the main limitations in saline-alkali soils. We investigated the effects on the microstructure, and the aerobic and anaerobic bacterial communities in the macroaggregates following addition of vermicompost and humic acid fertilizer to saline-alkali soil. These effects could enhance salt leaching and inhibit nitrogen losses in the topsoil. Vermicompost and humic acid fertilizer improved soil aggregate stability and the microstructure of macroaggregates (porosity, path tortuosity and effective porosity), which in turn increased soil permeability and salt leaching in saline-alkali topsoil. The improvement in aggregate microstructure affected the soil bacterial community of the macroaggregates by increasing the relative abundances of aerobic heterotrophs, such as Chloroflexi and Bacteroidetes. Additionally, vermicompost and humic acid fertilizer influenced nitrogen cycling by the macroaggregate microbial community, and stimulated nitrification by increasing archaeal and bacterial amoA gene copy numbers in the topsoil, but inhibited nitrite-reducing bacteria by decreasing nirS and nirK gene copy numbers. Furthermore, these amendments increased microbial N2O reduction by increasing nosZ gene copy numbers, suggesting that vermicompost and humic acid fertilizer have the potential to reduce N2O emissions in saline-alkali soil. In summary, vermicompost and humic acid fertilizer can ameliorate saline-alkali soils by replenishing organic matter, improving aggregate microstructure, and regulating the microbial community, which could increase salt leaching and inhibit nitrogen losses.

Efficiency of probiotic traits in plant inoculation is determined by environmental constrains

Management of the soil microbial community to increase crop productivity is one of the main challenges of modern agriculture, and bacterial inoculants can help to overcome this challenge. In this work, two plant growth-promoting (PGP) bacteria were evaluated under contrasting soil conditions, in order to test a rhizosphere ecology model. This model states that plants select for phosphate (P) solubilizers in poor nutrient soils and Indolic Compounds (ICs) producers in rich nutrient soils. Rice plants were single- or co-inoculated with strains of Burkholderia and Enterobacter genera in clayey and sandy soils. Diversity gradients were generated in each soil type using the dilution-to-extinction approach. Inoculant survival, colonization, and effect on plant biomass were evaluated, besides P solubilization and ICs production from both rhizospheric and endophytic bacterial communities. The PGP efficiency of the Burkholderia strain was highest in the sandy soil, which had the highest bacterial P solubilization potential, whereas the PGP efficiency of the Enterobacter strain was highest in the clayey soil, which had the highest bacterial ICs production potential. These behaviors occurred as hypothesized by the model, which can be useful for PGPB testing and bioprospection. We highlight a strong dependency of the Enterobacter strain on the diversity level as the most critical factor affecting PGP efficiency, possibly related to the increased influence of keystone taxa in lower diversity as indicated by network analysis.

Functional analysis of the OsNPF4.5 nitrate transporter reveals a conserved mycorrhizal pathway of nitrogen acquisition in plants

Low availability of nitrogen (N) is often a major limiting factor to crop yield in most nutrient-poor soils. Arbuscular mycorrhizal (AM) fungi are beneficial symbionts of most land plants that enhance plant nutrient uptake, particularly of phosphate. A growing number of reports point to the substantially increased N accumulation in many mycorrhizal plants; however, the contribution of AM symbiosis to plant N nutrition and the mechanisms underlying the AM-mediated N acquisition are still in the early stages of being understood. Here, we report that inoculation with AM fungus Rhizophagus irregularis remarkably promoted rice (Oryza sativa) growth and N acquisition, and about 42% of the overall N acquired by rice roots could be delivered via the symbiotic route under N-NO3- supply condition. Mycorrhizal colonization strongly induced expression of the putative nitrate transporter gene OsNPF4.5 in rice roots, and its orthologs ZmNPF4.5 in Zea mays and SbNPF4.5 in Sorghum bicolor OsNPF4.5 is exclusively expressed in the cells containing arbuscules and displayed a low-affinity NO3- transport activity when expressed in Xenopus laevis oocytes. Moreover, knockout of OsNPF4.5 resulted in a 45% decrease in symbiotic N uptake and a significant reduction in arbuscule incidence when NO3- was supplied as an N source. Based on our results, we propose that the NPF4.5 plays a key role in mycorrhizal NO3- acquisition, a symbiotic N uptake route that might be highly conserved in gramineous species.

Legacy of Amazonian Dark Earth soils on forest structure and species composition

AbstractAimAmazonian forests predominantly grow on highly weathered and nutrient poor soils. Anthropogenically enriched Amazonian Dark Earths (ADE), traditionally known as Terra Preta de Índio, were formed by pre‐Columbian populations. ADE soils are characterized by increased fertility and have continued to be exploited following European colonization. Here, we evaluated the legacy of land‐use and soil enrichment on the composition and structure in ADE and non‐ADE (NDE) forests.LocationEastern and southern Amazonia.Time periodPre‐Columbia – 2014.MethodsWe sampled nine pairs of ADE and adjacent NDE forest plots in eastern and southern Amazonia. In each plot, we collected soil samples at 0–10 and 10–20 cm depth and measured stem diameter, height, and identified all individual woody plants (palms, trees and lianas) with diameter ≥ 10 cm. We compared soil physicochemical properties, vegetation diversity, floristic composition, aboveground biomass, and percentage of useful species.ResultsIn the nine paired plots, soil fertility was significantly higher in ADE soil. We sampled 4,191 individual woody plants representing 404 species and 65 families. The floristic composition of ADE and NDE forests differed significantly at both local and regional levels. In southern Amazonia, ADE forests had, on average, higher aboveground biomass than other forests of the region, while in eastern Amazonia, biomass was similar to that of NDE forests. Species richness of both forest types did not differ and was within the range of existing regional studies. The differences in composition between large and small diameter tree recruits may indicate long‐term recovery and residual effects from historical land‐use. Additionally, the proportion of edible species tended to be higher in the ADE forests of eastern and southern Amazonia.Main conclusionsThe marked differences in soil fertility, floristic composition and aboveground biomass between ADE and NDE forests are consistent with a small‐scale long‐term land‐use legacy and a regional increase in tree diversity.

Phenotypic responses of foxtail millet (Setaria italica) genotypes to phosphate supply under greenhouse and natural field conditions.

Food insecurity is a looming threat for the burgeoning world population. Phosphorus (P), which is absorbed from soil as inorganic phosphate (Pi), is an essential macronutrient for the growth of all agricultural crops. This study reports phenotype analysis for P responses in natural field and greenhouse conditions, using 54 genotypes of foxtail millet (Setaria italica) representing wide geographic origins. The genotype responses were assessed in natural field conditions in two different seasons (monsoon and summer) under Pi-fertilized (P+) and unfertilized (P-) soil for eight above-ground traits. Enormous variations were seen among the genotypes in phenotypic responses for all the measured parameters under low P stress conditions. Variations were significant for plant height, leaf number and length, tillering ability and seed yield traits. Genotypes ISe 1234 and ISe 1541 were P+ responders, and the genotypes ISe 1181, ISe 1655, ISe 783 and ISe 1892 showed tolerance to low P for total seed yield. Genotypes that performed well under P- conditions were almost as productive as genotypes that performed well under P+ conditions suggesting some genotypes are well adapted to nutrient-poor soils. In the greenhouse, most of the genotypes produced changes in root architecture that are characteristic of P- stress, but to differing degrees. Significant variation was seen in root hair density and root hair number and in fresh and dry weight of shoot and root under P- stress. However, there was not much difference in the shoot and root total P and Pi levels of five selected high and low responding genotypes. We noticed contrasting responses in the greenhouse and natural field experiments for most of these genotypes. The leads from the study form the basis for breeding and improvement of foxtail millet for better Pi-use efficiency.

The Effect of Different Fire Regimes on Soil Properties in Wet Miombo woodlands of Zambia

Miombo woodlands occur on nutrient poor soils and generally experience a warm-to-hot climate with a dry cold season. Wet miombo areas, which receives more than 1,000 mm of average annual rainfall, are distinguished from dry miombo areas receiving less than 1,000 mm of average annual rainfall. Wet miombo woodland occurs over much of eastern Angola, northern Zambia, south western Tanzania and central Malawi in areas receiving more than 1000 mm rainfall per year. Canopy height is usually greater than 15 m, reflecting the generally deeper and moister soils which create favourable conditions for growth. The objective of this study was to investigate the effect of different fire regimes on soil properties in wet Miombo woodlands of Zambia. The study was conducted in Mwekera burning plots located in Mwekera National Forest No. 6 on the outskirts of Kitwe City. This study has uncovered some interesting relationships between fire and soil nutrients, soil chemical and physical properties. The complete fire protected treatment had significantly greater soil bulky density, organic soil carbon, phosphorus (P) and nitrogen (N) than other treatments. The late burning treatment had significantly greater soil pH, soil electrical conductivity, Calcium (Ca) and magnesium (Mg) than other treatments; however, a loss of soil organic matter during late burning fires likely resulted in increased bulk density and strength, and decreased water infiltration rates. Late burning fires also significantly increased soil pH, concentrations of extractable calcium, magnesium and carbon although to a lesser degree than early burning. Early burning fires did not lower soil potassium contents or alter soil chemical and physical properties. Our results indicate that despite differences in fire regimes, soil moisture, calcium and magnesium contents were not significantly different between early burning and late burning treatments. The results suggest that fire management did not affect soil moisture, calcium, and magnesium contents. Keywords: burning plots, fire regimes, soil properties, wet miombo woodlands DOI: 10.7176/JRDM/66-04 Publication date: June 30th 2020

First record of the gray-legged tinamou, Crypturellus duidae, and other poor-soil specialist birds from peatlands in the Putumayo River basin, Loreto, Peru

ABSTRACT Crypturellus duidae (Tinamidae) is a poor-soil specialist with isolated populations in Amazonia, and is considered restricted to white-sand forest habitats. We report the first record of C. duidae in a peatland forest in northern Peru, in the Putumayo River basin. Our record extends the known distribution of C. duidae between two disjoint areas of occurrence in Peru and Colombia, and shows its presence in peatland forest, another forest type on nutrient-poor soils. Additionally, we report the presence of other poor-soil specialist bird species that were previously registered in peatlands. Together with the new record of C. duidae, these bird records provide evidence of the diversity of poor-soil specialists in peatland forests.

Conservation tillage practices reduce nitrogen losses in the sloping upland of the Three Gorges Reservoir area: No-till is better than mulch-till

Nitrogen (N) losses contribute to a series of ecological problems such as non-point source pollution and aquatic eutrophication. The effects of tillage practices on N losses in the sloping upland of the Three Gorges Reservoir (TGR) area was studied by comparing N losses of three conservation tillage practices (no-till, mulch-till and minimum till) in a short-term field experiment with the conventional one. N losses from plots of the no-till and minimum till treatments were less than those from plots of the conventional tillage treatment by 19.03 and 6.33 kg N ha−1, respectively. Moreover, a meta-analysis of related data published between 1991 and 2017 was showed that conservation tillage (bootstrap confidence intervals of −57.35% to −7.86%) significantly reduced N losses more than conventional tillage. No-till (bootstrap confidence intervals of −48.76% to −13.23%) was more effective in reducing N losses than mulch-till (bootstrap confidence intervals of −56.65% to 14.52%). Moreover, the effect of no-till was stronger (bootstrap confidence intervals of −66.38% to −34.29% and −69.32% to −34.29%, respectively) on carbon-poor (<10 g kg−1) and N-poor (<0.7 g kg−1) soils. These results indicate that the conservation tillage practice significantly reduced N losses (especially N losses via surface runoff) in the sloping upland of the TGR area compared with conventional tillage and the no-till was more effective at reducing N losses than mulch-till in the nutrient-poor soil. Moreover, no-till did better in reducing the N losses in surface runoff than in subsurface leachate. Therefore, we recommend the use of no-till as a farming practice to reduce N losses and facilitate the sustainable development of agriculture in the sloping upland of the TGR area.

Deforestation and Subsequent Cultivation of Nutrient Poor Soils of Miombo Woodlands of Tanzania: Long Term Effect on Maize Yield and Soil Nutrients

The miombo woodlands of Tanzania have continued to be subjected to deforestation due to mainly agricultural expansion. Knowledge of long-term productivity of the subsequent land use can help to evaluate the sustainability of the existing land management systems. We used both socioeconomic and soil survey data to assess maize yield and selected soil properties, respectively, with an increasing cultivation period since conversion from miombo woodland. Data on maize production was collected from 121 households in three villages, while soil sampling was undertaken on 15 plots in one of the study villages. Soil samples were taken from miombo woodland and from croplands with cultivation periods varying from two to 52 years. Samples were taken at 0–10 cm and 10–20 cm depths and analyzed for the major plant nutrients. According to the results of the socioeconomic data analysis, continued cultivation of former miombo woodlands does not have a significant effect on maize yield. The results of the soil analysis also showed that the major plant nutrients on farmlands in both soil layers did not show a significant change from the adjacent miombo woodland and did not decline with increasing cultivation period. This indicates that the current farming system can maintain the levels of the major plant nutrients and thus soil productivity.