Effects Of Soil Fertility Research Articles

The effect of soil fertility on antioxidant enzymes activity in a subarctic woody species

The influence of major nutrients’ reserves (available to plants) – nitrogen (N), phosphorus (P), potassium (K) – in the top 25-cm layer of soil on the Karelian birch (Betula pendula Roth var. carelica (Mercl.) Hämet-Ahti) with non-figured and figured wood via the antioxidant enzymes’ activity was investigated. The analysis of sites in area where Karelian birch trees with varying degree of figured wood intensity were growing was carried out. The cambial zone of the sample trees during active cambial growth period was studied for the activity of AOS enzyme complex (superoxide dismutase (SOD); catalase (CAT); peroxidase (POD); polyphenol oxidase (PPO)). Cellulose content and lignin content were studied. It was noticed that the availability of major nutrients in the investigated sites had influence on the degree of figured wood intensity in Karelian birch plants. Thus, non-figured and figured Karelian birch plants that grew on sites with various levels of major nutrients’ reserves differed in the AOS enzymes’ activity, which was a consequence of different xylogenesis scenarios in the studied birch forms. It was supposed, that the certain site conditions (N, P, K levels) formation could affect the degree of figured wood intensity, cellulose and lignin content. The N level and P/N ratio had the most effects under the adequate K level. So AOS enzymes’ complex activity could indicate differences in Karelian birch wood quality in sites that differ in soil fertility (N, P, K levels).

Empirical survival model for European beech (Fagus sylvatica L.) seedlings in response to interactive resource gradients and (a-) biotic conditions within an experimental canopy gap study

The success of beech regeneration depends on resource availabilities, which are both heterogeneously distributed in forests and influenced by climate change impacts such as drought and heat waves. To ensure beech regeneration success in the future, it is therefore of great interest to understand the influences of different resource availabilities and their potentially interactive effects on beech seedling survival. In an experimental canopy gap study, we investigated the effects of direct (DIRSF) and diffuse (DIFFSF) solar radiation, soil fertility, groundwater influence, micro-site elevation, vegetation and root competition of overstorey trees on the survival of beech seedlings two years after planting in 2017. The inverse of fine root densities found for overstorey beech (BGRB) and oak (BGRO) was interpreted here as an approximation of the availability of below ground resources, mainly soil water. A logistic model demonstrated positive and interactive effects of DIFFSF, BGRB and soil fertility, emphasizing the complementary resource use pattern of beech seedlings. DIRSF showed a negative effect on survival that was enhanced on groundwater-dominated and higher elevated micro-sites and linked to intensified water limitation. The initial stature of seedlings, the presence and biomass of vegetation and BGRO had no significant effects on beech seedling survival. The unexpected extend to which DIFFSF affected beech seedling survival, the given significance of complementary effects of DIFFSF, BGRB and soil fertility, as well as found interactive effects of DIRSF are discussed in the context of the 2018/19 drought event. Our results suggest that silvicultural measures, such as the creation of larger gaps, can significantly improve resource availabilities, providing an opportunity to increase survival of beech seedlings in the face of climate change impacts.

Poultry Manure Induced Garden Eggs Yield and Soil Fertility in Tropical and Semi-Arid Sandy-Loam Soils

Synthetic nitrogen fertilizer use comes with unsustainable financial and environmental costs, making it not attractive to small-scale and organic farmers. Poultry manure (PM) when available is a primary fertilizer source for small-scale and organic farmers but there is still limited research on its effects of specific crops and soil fertility under specific practices. The study investigated PM effects on garden egg in three seasons in Ghana and PM effects soil fertility in sandy-loam soils of Arizona after three years under flood irrigation and no-till. The PM application improved garden egg growth (dry matter by 73%) and increased yield by 66% in slightly acidic sandy-loam tropical soils, which could be related to soil mineral improvement. In the semi-arid soil, three years PM application increased cation exchange capacity (41%), P (471%), K (18%), S (244%), Ca (45%), Mg (31%), Zn (5%) and Mn (19%) with reduction in nitrate (−26%), Fe (−38%) and Cu (−11%). The reduction in the nitrate and Fe in the semi-arid Arizona cropland could be associated to flood irrigation and high soil pH, respectively. To gain the full potential from PM applications, best management practice is recommended to reduce nitrate leaching.

Cattle manure and bio-nourishing royal jelly as alternatives to chemical fertilizers: Potential for sustainable production of organic Hibiscus sabdariffa L.

For sustainable and organic farming, organic manures such as cattle manure (CMn) and bio-nutritious substances such as royal jelly (RJ) should be used as complete or at least partial alternatives to chemical fertilizers (CFs). Therefore, two consecutive trial seasons (2018 and 2019) were conducted to study the effect of soil fertilization with CMn and/or CFs in combination with foliar spraying with RJ on growth, yield, and chemical composition of roselle (Hibiscus sabdariffa L.) plant and seed. The results indicated that spraying roselle plants with RJ resulted in a significant increase in all parameters studied over the control; however, this increase was enhanced when RJ was combined with soil fertilization. The highest values for most of the growth traits, chemical composition of seeds, sepal anthocyanin and vitamin C contents, and sepal acidity were obtained by applying 2 or 4 g RJ L−1 + (30 m3 CMn ha−1 + 50 % dose CFs). In addition, the highest values for yield components and plant chemical composition were obtained by applying 2 or 4 g RJ L−1 + (0 m3 CMn ha−1 + full dose CFs). The results also indicated that applying CMn in combination with RJ gave values mostly close to those of CFs treatment. In conclusion, the results recommend the use of RJ (2 g L−1 as a foliar feeding) along with CMn (30 m3 ha−1) as a partial alternative to chemical fertilizers for sustainably producing healthy roselle sepals.

Above-ground biomass storage potential in primary rain forests managed for timber production in Costa Rica

Tropical forests play a fundamental role in mitigating climate change through storage of carbon in above- and below- ground biomass. Their mitigation potential is, however, affected by significant greenhouse gas emissions through tropical deforestation or forest degradation. Mitigating degradation caused by conventional logging is therefore an important challenge for silvicultural management, and various reduced impact logging techniques seek to reduce biomass loss and other logging impacts during forest logging activities.Little knowledge exists about the potential of sustainable management for maintaining and restoring the climate change mitigation capacity of tropical forests. Our research contributes to knowledge about this potential, as our aim is to evaluate the above-ground biomass (AGB) stock of tropical forests managed for sustainable timber production and compare it with that of intact primary forests. We also determine the environmental and spatial factors that influence AGB.We estimated the AGB of 141 permanent sampling plots in Costa Rican tropical forests (71 plots set up in areas managed for timber production forests and 70 plots set up in areas with intact primary forests) using data for the 2000–2015 period. We compared the AGB of timber production forests with that of primary forest using linear mixed models and examined the relationship between forest AGB and climate, soil fertility and spatial variables (PCNM eigenvalues) using variation partitioning (VARPART) and multiple linear regression in the mixed model framework.Mean AGB was higher in forest plots set up in areas managed for timber production than in plots set up in areas with intact primary forests. In VARPART, spatial variables had the strongest effect on AGB with a small but significant effect of soil fertility. Regression showed potassium levels in the soil to be positively related to AGB. There was no significant effect of climate, probably because of the short temperature and precipitation gradients.Sustainable forest management in these Costa Rican forests managed for timber production has enabled them to store as much carbon in biomass as primary forests, due to the low intensity logging and sustainability criteria stipulated by the country’s forestry legislation. As a result, sustainable forest management, in addition to providing a sustainable timber ecosystem service, is also a natural climate solution, maintaining the mitigation potential of Costa Rica’s tropical forests in the current climate context.

The anniversary conference "Structural Components of Forest Ecosystems: ecology, conservation and management" held in honour of Prof. Nicolae Donita

The anniversary conference "Structural Components of Forest Ecosystems: ecology, conservation and management" held in honour of Prof. Nicolae Donita

ДОСЛІДЖЕННЯ З ҐРУНТОВОГО УДОБРЕННЯ ТА ПОЗАКОРЕНЕВОГО ПІДЖИВЛЕННЯ В НАСАДЖЕННІ ГРУШІ

Biological, meteorological and agro-technical factors have an impact on the nutrition level of fruit and berry crops. To reach high productivity, agricultural crops are to be provided with nutrient substances in a proper form and optimal amount. The addition of important components at critical stages of the plant development gives an impulse to create high and quality yield. Fertilization is aimed at satisfying the feeding needs of the trees in certain soil-climatic conditions; the dose is determined for separate elements according to the peculiarities of a fruit crop, a pomological cultivar, a rootstock and a tree age, also mineral nutrition elements in the soil and the possibility for a fruit crop to use them are taken into consideration. The nutrient requirements of fruit trees vary during the growing season. From the moment of budding to flowering, the need for nitrogen increases, the need for potassium and phosphorus constantly increases during the growing season. Rational mineral fertilization in pear-tree orchards should be based on the results of the soil and leaf analyses as well as on a visual estimation of the growth and fruit bearing of the trees (for example, nitrogen, iron). Unfortunately, it is very common for gardens to be fertilized blindly, without controlling the nutrient content of the soil. Excessive fertilization can both decrease fruit yielding capacity and quality and pollute the environment because of the accumulation of fertilizers in the soil and their washing out into soil and surface waters. The survey of literature sources concerning the effect of soil fertilization and top dressing on the growth and general productivity of pear-tree orchards was made. As a result of the analysis made, it has been established that at present no recommendation as to the application of fertilization in pear-tree orchards is available, because most of them were suggested for apple-tree and pear-tree orchards together. However, there is a difference in mineral nutrition of a pear-tree, in particular those on weak rootstock. Which is why, it is relevant to consider the issue of the development of an optimal fertilization system of intensive pear-tree orchards on a vegetative rootstock

On the general relationship between plant height and aboveground biomass of vegetation stands in contrasted ecosystems.

Ecological communities are unique assemblages of species that coexist in consequence of multi-causal processes that have proven hard to generalize. One possible exception are processes that control the biomass packing of vegetation stands; the amount of aboveground standing biomass expressed per unit volume. In this paper, I investigated the empirical and geometric underpinnings of biomass packing in terrestrial plant communities. I support that biomass packing in nature peaks around 1 kg m-3 across contrasted contexts, ranging from grasslands to forest ecosystems. Using published experimental and long-term survey data, I show that expressing biomass per unit volume cancels the effects of air temperature, species richness and soil fertility on aboveground stocks, thus providing a general comparative measure of storage efficiency in plant communities.

Effect of ground addition and foliar spraying of bio -fertilizer on some vegetative growth characteristics of local lemon (Citrus lemon L.) Saplings

This study was carried out in the lath house of the Department of Biology -College of Education for Pure Sciences – University of Anbar, during the autumn season (2020) with the aim of studying the effect of soil fertilization and foliar application of (Bio health) bio fertilizer on some of the vegetative growth characteristics of local lemon saplings. A factorial experiment with two-factors experiment was carried out according to the randomized complete block design (RCBD), included 16 treatments, with four replicates, the first factor (A) was the soil fertilization with at four concentrations of 0, 2, 4 and 6 g.L-1, the second factor (B) was foliar application with at four concentrations 0, 1, 2 and 3 g.L-1, the results showed the superiority of the treatment of soil fertilization with a concentration of 6 g.L-1 and the foliar application of 3 g.L-1, and the interaction between them was significant in the characteristics of scion diameter, leaves content of relative chlorophyll, leaf area and leaves area, as for the treatment, Foliar application with a concentration of 2 g.L-1 and 3 g.L-1 showed a significant increase in the characteristic of plat height and rootstock diameter respectively, while the interaction between soil fertilization and foliar application of 2 g.L-1 showed the best result in the characteristic of plant height, while the interaction between the soil fertilization treatments 1 g.L-1 and foliar application at a concentration of 2 g.L-1 showed the best diameter of rootstock.

Ant’s choice: The effect of nutrients on a key ant–hemipteran mutualism

Soil fertility is understood to act in many indirect ways, in addition to directly providing nutrients to plants. Given that higher order indirect interactions frequently are key to understanding community structure, it would be natural to expect that indirect mutualisms should be as important as other interactions in generating such structure. Although mutualisms are ubiquitous in nature, exploring the myriad ways in which they interconnect with other elements of a system is less common. That soil fertility has an indirect effect on community structure is well known, suggests that soil fertility may be important in determining the effect of mutualisms on the structure of the ecological communities in which they are embedded. Here we report on a laboratory study that specifically examines the direct connection between the behavior of a mutualist and nutritional properties of the soil. We tested the effects of soil fertilization (high, medium and low levels) on the Azteca seriseasur–Coccus viridis mutualism on coffee plants in Mexico. We found that ants foraged significantly more on plants that were infected with C. viridis over control plants. Moreover, ants preferred to tend C. viridis on high fertilized over medium and low fertilized plants. This study highlights the importance of the links between soil nutrient properties and their effects on a key ant-hemipteran mutualism, illustrating the cascading effects on other interactions involving this keystone ant species.

Grain yield and physiological parameters of gas exchange in common bean as a function of copper fertilization

Conducting a field study to investigate the effects of foliar and soil fertilization with copper on the nutritional and physiological parameters and grain yield of common bean. The experimental design was a randomized block, in a 2 x 5 factorial scheme. The first factor was the site of application of copper fertilization. The second factor was copper doses: 0, 1, 2, 3, and 4 kg ha-1 (6 replicates). The following were evaluated: leaf nitrogen and copper contents, relative chlorophyll index (RCI), gas exchange, photochemical efficiency of photosystem II, and grain yield. The data were subjected to analysis of variance and F test (p-value < 0.05), using the Scott & Knott for qualitative data and polynomial regression for quantitative data. Leaf Cu content was higher with soil application (4% and 28%), both at 24 and 45 DAE, respectively. Net photosynthesis reached a maximum index of 18.77 µmol m-2 s-1 with foliar Cu fertilization at the dose of 4 kg ha-1. The application of 2.0 kg ha-1 Cu was the one that led to the highest grain yields; however, soil application stood out with a yield about 12% higher of the foliar. Soil fertilization proved to be more efficient in terms of Cu absorption and RCI rates, improving grain yield (12%) in relation to foliar, especially at the dose of 2 kg ha-1. The dose of 2 kg Cu ha-1 provided the best differential profit, reaching US$ 581.96 ha-1 and US$ 503.01 ha-1 for soil and foliar application, respectively.

Subalpine grassland productivity increased with warmer and drier conditions, but not with higher N deposition, in an altitudinal transplantation experiment

Abstract. Multiple global change drivers affect plant productivity of grasslands and thus ecosystem services like forage production and the soil carbon sink. Subalpine grasslands seem particularly affected and may serve as a proxy for the cold, continental grasslands of the Northern Hemisphere. Here, we conducted a 4-year field experiment (AlpGrass) with 216 turf monoliths, subjected to three global change drivers: warming, moisture, and N deposition. Monoliths from six different subalpine pastures were transplanted to a common location with six climate scenario sites (CSs). CSs were located along an altitudinal gradient from 2360 to 1680 m a.s.l., representing an April–October mean temperature change of −1.4 to +3.0 ∘C, compared to CSreference with no temperature change and with climate conditions comparable to the sites of origin. To uncouple temperature effects along the altitudinal gradient from soil moisture and soil fertility effects, an irrigation treatment (+12 %–21 % of ambient precipitation) and an N-deposition treatment (+3 kg and +15 kg N ha−1 a−1) were applied in a factorial design, the latter simulating a fertilizing air pollution effect. Moderate warming led to increased productivity. Across the 4-year experimental period, the mean annual yield peaked at intermediate CSs (+43 % at +0.7 ∘C and +44 % at +1.8 ∘C), coinciding with ca. 50 % of days with less than 40 % soil moisture during the growing season. The yield increase was smaller at the lowest, warmest CS (+3.0 ∘C) but was still 12 % larger than at CSreference. These yield differences among CSs were well explained by differences in soil moisture and received thermal energy. Irrigation had a significant effect on yield (+16 %–19 %) in dry years, whereas atmospheric N deposition did not result in a significant yield response. We conclude that productivity of semi-natural, highly diverse subalpine grassland will increase in the near future. Despite increasingly limiting soil water content, plant growth will respond positively to up to +1.8 ∘C warming during the growing period, corresponding to +1.3 ∘C annual mean warming.

The effects of soil compaction and fertility on a threatened endemic palm species in a global conservation hotspot

Butia eriospatha (Mart. ex Drude) Becc. is a subtropical endemic palm tree that occurs in the Southern Brazilian Highlands. A vast area of its natural habitat has been lost by land-use changes, placing the species at high risk of extinction. Here, we investigated how environmental variables impact the structure of B. eriospatha populations. We randomly allocated 14,100 × 100 m plots, where all palms had the diameter at breast height (dbh) and the total height (th) measured. In the same plots, we collected data on edaphic, topographic, and land-use variables. The data were analysed by frequency histograms, factor analysis of mixed data, and regression trees. B. eriospatha’s size class frequencies tended towards a normal distribution, with few small individuals. We found that plots with flatter terrain had more compacted soils. The structure and biometrics traits of B. eriospatha’s populations were affected by the interaction between soil compaction and fertility. We conclude that sites with lower fertility and more compacted soils showed populations with lower abundance and basal area, and smaller individuals. Sustainable practices of soil management are required to prevent the species from becoming locally extinct.

Effect of rainfall and soil fertility on total phenol and tannin contents in Cenostigma microphyllum (Mart. ex G. Don) E. Gagnon & G.P. Lewis (Fabaceae)

The study examined the total phenol and tannin contents in stem bark and leaf tissues of the medicinal species Cenostigma microphyllum (Mart ex. G. Don) E. Gagnon & G. P. Lewis distributed under different rainfall amounts and soil fertility levels in the Caatinga, the largest nucleus of Seasonally Dry Tropical Forest and Woodlands in the Neotropics. Using colorimetric method (Folin–Ciocalteu to total phenol content and casein precipitation to total tannin content), it was shown that both phenol and tannin content was significantly higher in the leaves than in the stem bark. Soil fertility affected negatively only the total phenol content. No relationship was observed between rainfall and compounds, and between soil fertility and total tannin content. Thus, our findings indicate that although water-deficit stress is a limiting factor in arid and semi-arid regions, soil fertility is also an abiotic factor that affect the production of phenolic compounds. Moreover, the concentration of such metabolites changes according to the class of compound and plant tissue analyzed.

Weather Differentials and Discount Rate Impact on Farmers’ Net Revenue: Modeling Results from Ghanaian Data Focusing on Different Agro-Climatic Zones

In most developing countries, climate variabilities and discount rate played an integral role in the decision-making of farmers, which mostly affect their net revenue. Our study employs Ricardian models to empirically verify this hypothesis using data collected from three major agro-climatic zones in Ghana. We particularly estimated the comparative effect of climate change variability, discount rate, and soil fertility; due to trade-off effect of certain farm practices in response to climate change across major climatic zones and also the fact that discount rate becomes an extremely critical issue in formulating and evaluating conservation and management policy to address climate change. The result indicates that discount rate has a positive and significant effect on the farmers’ net revenue. Further, effect of changes in temperature on food crop production and hence net revenue is more felt in the forest and savannah zones. On the other hand, an increase in rainfall has significant negative effects on crop net revenues and whole-farm net revenue, but a positive effect on net revenue of farmers in the savannah zone. We also found a significant increase in soil fertility to increase crop net revenues.

Selenium Biofortification of Wheat as a Strategy to Improve Human Nutrition

This paper analyses the effects of soil and foliar fertilization with sodium selenate (VI) on the selenium content in spring wheat grain. The research was carried out at the Departmental Experimental Station of the Institute of Agriculture WULS in Skierniewice in 2018 and 2019. The dose of selenium used was 5.00 g Se·ha−1 in various development stages of spring wheat. The results showed that selenium fertilisation did not affect the size of the grain yield, but both soil and foliar fertilisation significantly increased the content of selenium in wheat grain compared to the control group. The highest Se content was obtained with the method of soil fertilisation combined with the foliar application with a total dose of 10.00 g·ha-1 Se in the stem elongation phase (S + F2), and in the tillering and stem elongation phase (S + F1 + F2), which resulted in the values of 0.615 and 0.719 mg·kg−1 Se in grain, respectively. On this basis, it was concluded that the best time to carry out foliar fertilisation treatment is in the stem elongation phase (BBCH 30–39). The results show that the greatest increase in selenium content in the grain is achieved with soil and foliar fertilisation combined.

Soil fertilization affects the abundance and distribution of carbon and nitrogen cycling genes in the maize rhizosphere

Soil microbes perform important functions in nitrogen and carbon cycling in the biosphere. Microbial communities in the rhizosphere enhance plants’ health and promote nutrient turnover and cycling in the soil. In this study, we evaluated the effects of soil fertilization with organic and inorganic fertilizers on the abundances and distribution of carbon and nitrogen cycling genes within the rhizosphere of maize plants. Our result showed that maize plants through rhizosphere effects selected and enriched the same functional genes glnA, gltB, gudB involved in nitrogen cycle as do high compost and low inorganic fertilizer treatments. This observation was significantly different from those of high doses of inorganic fertilizer and low compost manure treated soil. Only alpha amylase encoding genes were selectively enriched by low compost and high inorganic fertilized soil. The other treatments only selected xynB (in Cp8), lacZ (Cp4), bglA, pldB, trpA (N2), uidA (N1) and glgC, vanA (Cn0) carbon cycling genes in the rhizosphere of maize. Also Actinomycetales are selected by high compost, low inorganic fertilizer and control. The control was without any fertilization and the soil was planted with maize. Bacillales are also promoted by low compost and high inorganic fertilizer. This indicated that only microbes capable of tolerating the stress of high dose of inorganic fertilizer will thrive under such condition. Therefore, soil fertilization lowers nitrogen gas emission as seen with the high abundance of nitrogen assimilation genes or microbial anabolic genes, but increases carbon dioxide evolution in the agricultural soil by promoting the abundance of catabolic genes involve in carbon cycling.

Short-term cover crop carbon inputs to soil as affected by long-term cropping system management and soil fertility

Cover crops (CC) increase soil fertility via recycling of nutrients such as nitrogen (N) and buildup of soil organic matter, whereby CC contributes to climate change mitigation. The carbon (C) input to soil occurs via the input of plant material (shoot and root) and via phyllo- and rhizodeposition. However, the quantity of phyllo- and rhizodeposition from CC is largely unexamined, although this component potentially has a large contribution to microbial stabilization of C. Isotopic labeling with 13C to trace C flows and 15N to determine N2-fixation was conducted to test the short-term effect of the inclusion of winter vetch as a legume species to a CC mixture. The CC mixtures were established in a long-term experiment (1997–2019) with varying use of manure and CC cropping to test the effect of soil fertility on the behavior of the newly established CC mixtures. A significant reduction in the relative net phyllo- and rhizodeposition was observed with higher soil fertility. Interestingly, the quantity of net phyllo- and rhizodeposition was also reduced with higher soil fertility due to the lower relative phyllo- and rhizodeposition, despite a significantly higher CC biomass. Importantly, adjusting for unrecovered root fragments more than halved the calculated phyllo- and rhizodeposition, indicating that many published estimates are substantially overestimated. The use of CC during autumn provides an important window for C storage with both the input of plant biomass and belowground C investment being drivers of C storage.

Abrasive Weeding as a Vehicle for Precision Fertilizer Management in Organic Vegetable Production

Abrasive weeding is a nonchemical weed control tactic that uses small, gritty materials propelled with compressed air to destroy weed seedlings. Organic fertilizers have been used successfully as abrasive grits to control weeds, but the goal for this study was to explore the effects of fertilizer grit, application rates, and background soil fertility on weeds, plant available nitrogen (N) uptake, and crop yield. Field trials were conducted in organic ‘Carmen’ sweet red pepper (Capsicum annuum) and organic ‘Gypsy’ broccoli (Brassica oleracea var. italica) and treatments included organic fertilizer grit (8N–0.9P–3.3K vs. 3N–3.1P–3.3K), grit application rates (low vs. high), compost amendments (with and without), and weedy and weed-free controls. Weed biomass was harvested at 84 days and 65 days after transplanting for pepper and broccoli, respectively. Simulated total plant available N (nitrate + ammonium) uptake was measured with ion exchange resin stakes between 7 and 49 days after the first of two grit applications. Produce was harvested at maturity, graded for marketability, and weighed. The higher grit application rate, regardless of fertilizer type, reduced the weed biomass by 75% to 89% for pepper and by 86% to 99% for broccoli. By 5 weeks after the first grit application, simulated plant N uptake was greatest following grit application with the 8% N fertilizer, followed by the 3% N fertilizer, and lowest in the weedy control. The high grit application rate of 8% N fertilizer increased pepper yield by 112% compared with the weedy control, but it was similar to that of the weed-free control. Broccoli was less responsive to abrasive grits, with yield changes ranging from no difference to up to a 36% increase (relative to the weedy control) depending on the application rate and compost amendment. This is the first evidence indicating that the nutrient composition of organic fertilizer abrasive grits can influence in-season soil N dynamics, weed competition, and crop yield. The results suggest that abrasive weeding technology could be leveraged to improve the precision of in-season fertilizer management of organic crops.

Nutrient supply modulates species interactions belowground: dynamics and traits of fine roots in mixed plantations of Eucalyptus and Acacia mangium

Belowground interactions are still poorly understood in mixed-species forests. We investigated the effects of soil fertility on belowground processes in mixed planted forests. The dynamics and traits of Eucalyptus and Acacia mangium fine roots (diameter < 2 mm) in plantations with 50% of each species were studied in a randomized block design established in a nutrient depleted soil. Stands with NPK fertilization applied at planting (F+) were compared to unfertilized stands (F-). In the 0–15 cm soil layer, Eucalyptus root mass density (RMD) was higher than Acacia RMD by 50% in F+ and 10% in F-, considering both ages. At 34 months of age, Eucalyptus RMD was 94% higher near Acacia trees than near Eucalyptus trees in F-. In this layer, Eucalyptus specific root length (SRL) was 21% higher than Acacia SRL at 16 months of age and was 10% higher in F- than in F+ at 34 months of age. The cumulative Eucalyptus fine root length production between 16 and 34 months was 66% higher in F- than in F+ in the 0–1 m soil layer. Fertilization increased the competition between species and led to a partial exclusion of Acacia fine roots from the nutrient-rich topsoil. Soil exploration by Eucalyptus roots in the vicinity of Acacia trees was higher in F- than in F+, which suggests that unfertilized trees benefited from facilitation through higher soil N availability and direct N transfer from Acacia trees.