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Aims Cover crops play an important role in soil fertility as they can accumulate large amounts of nutrients. This study aimed at understanding the nutrient uptake capacity of a wide range of cover crops and at assessing the relevance of acquisition strategies. Methods A field experiment was conducted to characterize 20 species in terms of leaf and root traits. Plant traits were related to nutrient concentration and shoot biomass production with a redundancy analysis. Acquisition strategies were identified using a cluster analysis. Results Root systems varied greatly among cover crop species. Five nutrient acquisition strategies were delineated. Significant amounts of nutrients (about 120 kg ha⁻¹ of nitrogen, 30 kg ha⁻¹ of phosphorus and 190 kg ha⁻¹ of potassium) were accumulated by the species in a short period. Nutrient acquisition strategies related to high accumulations of nutrients consisted in either high shoot biomass and root mass and dense tissues, or high nutrient concentrations and root length densities. Species with high root length densities showed lower C/N ratios. Conclusions The same amounts of nutrients were accumulated by groups with different acquisition strategies. However, their nutrient concentrations offer different perspectives in terms of nutrient release for the subsequent crop and nutrient cycling improvement.

In horticultural practice accelerated plant development and particularly earlier flowering, has been reported with microalgae applications. Therefore, the objective of this work was to study the effects of foliar spraying with Scenedesmus sp. and Arthrospira platensis hydrolysates on Petunia x hybrida plant development and leaf nutrient status. Three treatments were tested: T1 (foliar application with water, the control), T2 (foliar application with Arthrospira), and T3 (foliar application with Scenedesmus). Foliar spraying was applied five times (0, 14, 28, 35, and 42 days after transplanting). The concentration of both microalgae was 10 g L−1. At the end of the trial biometric parameters and nutrient concentration in photosynthetic organs (the leaves) were measured. The results of this assay show that foliar application of Scenedesmus accelerated plant development in terms of higher rates of root growth, leaf and shoot development, and earliness of flowering. Arthrospira enhanced the root dry matter, the number of flowers per plant, and the water content. Nevertheless, a reduction was found in the conductive tissue (stem + petiole) dry weight with Arthrospira compared with Scenedesmus and the control. The results also show that microalgae hydrolysate supply can improve the plant nutrient status. Based on these results, it is advisable to use Scenedesmus hydrolysates in foliar applications to increase the blooming of Petunia x hybrida.

1. There is a growing interest in understanding the relationship between diversity and below-ground productivity due to the critical contribution of below-ground systems to overall terrestrial productivity. Yet, the temporal (seasonal and developmental) changes in diversity effects on below-ground productivity and their underlying mechanisms remain unclear. 2. We hypothesized that (i) diversity effects on fine root productivity increase with stand development, and (ii) increased diversity effects associated with stand development result from augmented horizontal soil space utilization, increased forest floor depth for rooting, enhanced effects in nutrient-poor soil layers and/or foraging towards high nutrient availability. 3. We investigated the effects of tree species diversity on fine root productivity by sampling 18 stands dominated by single species and their mixtures in post-fire boreal forests of two stand ages (8 and 34 years following stand-replacing fire). Species evenness was significantly higher in species mixtures than in single-species-dominated stands at both age classes, while species richness did not differ across stand types and age classes. 4. We found that the annual fine root production was higher in mixtures than the mean of single-species-dominated stands in both stand ages, with a significantly higher magnitude of effects in the 34-year-old than 8-year-old stands. Mixtures had higher horizontal soil volume filling than single-species-dominated stands with a more pronounced increase in the 34-year-old than 8-year-old stands. Compared with the 8-year-old stands, the 34-year-old stands had increased forest floor depth and greater overyielding with soil depth, and their fine root productivity was more responsive to the vertical variation in soil phosphorus concentrations among soil layers. 5. Synthesis. Our results provide evidence for increasing positive diversity effects on fine root productivity with stand development in heterogeneous natural forests. Moreover, our results indicate that the increased positive diversity effects with stand development was the result of multiple mechanisms, including higher horizontal soil volume filling, a thicker forest floor layer for rooting, a higher magnitude of complementarity in nutrient-poor deep soil layers and stronger nutrient foraging towards soil layers with high nutrient concentrations in older than younger stands.

Effective nutrient management requires understanding nutrient uptake at various growth stages and nutrient removal by the harvested portion. Information on nutrient accumulation was provided by some older literature, and a few researchers have focused on this issue in this modern period with modern hybrids and improved corn cultivation practices. While almost all the studies were conducted in northern states of the US, information for the Southern Great Plains is still limited. To bridge this knowledge gap, a 2-year field study was conducted in a rain-fed corn production system. The study aimed to evaluate the impact of nitrogen (N), phosphorus (P) and potassium (K) fertilization on N, P, and K contents in aboveground plants at different growth stages. Pre-plant application of N (0, 67, 133 kg N ha−1), P (0 and 20 kg ha−1) and K (0 and 60 kg ha−1) fertilizers was done. Results from our study revealed that nutrient uptake values, pattern and dynamics depend on environmental conditions, soil type and management practices. N concentration in plants showed a linear response to N application rate while P and K concentrations were unaffected by NPK fertilization rates. Total N, P and K uptake was primarily driven by N application rate, showing a linear increase with higher N rates. Co-application of P and K with N did not significantly affect nutrient concentration and uptake.

Background and aims Leaf nutrient concentrations are predictors of plant growth variation and crucial for biogeochemical cycling. We aimed to explore the effects of phylogeny, leaf habit and soil chemistry on leaf nutrient concentrations in tropical karst environments. Methods We sampled top-soils and leaves of co-existing evergreen and deciduous tree species along the continuum of mountain valley, slope and peak in a tropical karst seasonal rainforest. We used phylogenetic comparative methods to determine how leaf nutrient concentrations varied in response to phylogeny, leaf habit and soil chemistry and interacted with each other. Results Tree species had large inter- and intra-nutrient variability and were characterized by the combination of P limitation and Ca hyperaccumulation in leaves. The phylogenetic signals in leaf nutrient concentrations were not significant but increased with decreasing evolutionary rates as a result of the best fitted evolutionary process, i.e., stabilizing selection towards an optimum value. Compared with deciduous species, evergreen species had lower nutrient concentration requirements to fulfill specific biochemical functions in leaves. Along the valley-slope-peak continuum, the correlations between leaf and soil nutrient concentrations were positive for Ca, Mg, P, Cu and Zn and negative for N, S, K and Fe. The strength of interactions differed among leaf nutrients and this largely depended on the divergent biochemical functions among leaf nutrients. Conclusions Our results suggest that stabilizing selection combined with the biochemical constraints could select the locally adapted evergreen and deciduous species with sufficient phylogenetic variations to produce leaf nutrient concentrations and certain nutrient combinations that should be well-fitted in tropical karst environments.

Beta diversity, the spatial or temporal variability of species composition, is a key concept in community ecology. However, our ability to predict the relative importance of the main drivers of beta diversity (e.g., environmental heterogeneity, dispersal limitation, and environmental productivity) remains limited. Using a comprehensive data set on stream invertebrate assemblages across the continental United States, we found a hump-shaped relationship between beta diversity and within-ecoregion nutrient concentrations. Within-ecoregion compositional dissimilarity matrices were mainly related to environmental distances in most of the 30 ecoregions analyzed, suggesting a stronger role for species-sorting than for spatial processes. The strength of these relationships varied considerably among ecoregions, but they were unrelated to within-ecoregion environmental heterogeneity or spatial extent. Instead, we detected a negative correlation between the strength of species sorting and nutrient concentrations. We suggest that eutrophication is a major mechanism disassembling invertebrate assemblages in streams at a continental scale.

Background and aims Bark contains a substantial fraction of the nutrients stored in woody biomass, however the degree of functional coordination of bark, wood, and foliar nutrient pools, and its relationship to soil nutrient availability remains poorly understood. Methods Bark thickness and nitrogen, phosphorus, potassium, calcium, and magnesium concentrations were measured in 23 tree species present in two premontane wet tropical forests in western Panama differing in soil nutrient availability. Bark data were combined with existing wood and leaf data from the same species. Results Bark nutrients were positively correlated with leaf and wood nutrients for all elements. The low fertility site had both lower bark nutrient concentrations and thicker bark, driven primarily by species compositional differences between sites, and secondarily by intraspecific variation. Across species, bark nutrient concentration varied 4 to 25 fold, with the highest variation for calcium. Overall, bark accounted for the largest percent of Ca in above-ground biomass nutrient pools (22–82%) and a large fraction of the other nutrients studied (N: 6–53%, P: 5–50%, K: 4–40%, and Mg: 2–35%). Conclusions Bark represents a substantial, and highly variable, pool of biomass nutrients. The functional role of bark nutrients, the causes and consequences of this variation, and its relation to other bark traits, including bark thickness, deserve further study.

Plant nutrient concentration and resorption play a major role in determining primary production and development of forests. Yet how plant nutrient concentration and resorption respond to altered interannual precipitation and how interannual precipitation variability mediates the responses of plant nutrient concentration and resorption to N addition remain uncertain. Here, we examined the responses of needle nutrient (N and P) concentrations of all aged classes, nutrient resorption efficiency, and proficiency to N addition (10 g N m−2 year−1) over a 4‐year period (from 2016 to 2019) that experienced high variability in precipitation in a Mongolian pine plantation in a semiarid region of northeast China. There were significant interannual variations in N and P concentrations in all aged needles and litters, N and P resorption efficiency, as well as soil inorganic N and available P concentrations in the control plots. Increased precipitation resulted in increased needle nutrient concentrations across the four consecutive years. However, needle nutrient concentrations did not covary with soil available nutrients. The responses of needle N resorption efficiency (NRE) to N addition differed across the four years, with N addition decreasing NRE in wet years, but not in dry years. Taken together, our results showed that foliar nutrient concentrations are sensitive to altered annual precipitation and that different interaction effects exist between N addition and sampling year for different nutrient variables. Such differential responses highlight the challenge of predicting effects of N addition on nutrient cycling over temporal scales.

Salinity stress is a significant challenge in agricultural production. When soil contains high salts, it can adversely affect plant growth and productivity due to the high concentration of soluble salts in the soil water. To overcome this issue, foliar applications of methyl jasmonate (MJ) and gibberellic acid (GA3) can be productive amendments. Both can potentially improve the plant’s growth attributes and flowering, which are imperative in improving growth and yield. However, limited literature is available on their combined use in canola to mitigate salinity stress. That’s why the current study investigates the impact of different levels of MJ (at concentrations of 0.8, 1.6, and 3.2 mM MJ) and GA3 (0GA3 and 5 mg/L GA3) on canola cultivated in salt-affected soils. Applying all the treatments in four replicates. Results indicate that the application of 0.8 mM MJ with 5 mg/L GA3 significantly enhances shoot length (23.29%), shoot dry weight (24.77%), number of leaves per plant (24.93%), number of flowering branches (26.11%), chlorophyll a (31.44%), chlorophyll b (20.28%) and total chlorophyll (27.66%) and shoot total soluble carbohydrates (22.53%) over control. Treatment with 0.8 mM MJ and 5 mg/L GA3 resulted in a decrease in shoot proline (48.17%), MDA (81.41%), SOD (50.59%), POD (14.81%) while increase in N (10.38%), P (15.22%), and K (8.05%) compared to control in canola under salinity stress. In conclusion, 0.8 mM MJ + 5 mg/L GA3 can improve canola growth under salinity stress. More investigations are recommended at the field level to declare 0.8 mM MJ + 5 mg/L GA3 as the best amendment for alleviating salinity stress in different crops.

A screen house experiment was conducted to evaluate the effects of Tithonia diversifolia biochar on selected soil physicochemical properties. The study included five treatments with Tithonia diversifolia biochar applied at rates of 0, 10, 20, 30, and 40 t ha − 1 , arranged in a completely randomised design with three replicates. Surface soil (0–15 cm depth) from the Iwo soil series (sandy loam) was collected from the Teaching and Research Farm of Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria. Each 10 kg soil sample was thoroughly mixed with the respective biochar rate and maintained at field moisture capacity for four weeks in the screen house before sowing broccoli seeds. Soil samples were analyzed for particle size distribution, bulk density, porosity, moisture content, pH, organic carbon, total nitrogen, available phosphorus, exchangeable potassium, calcium, and magnesium. Agronomic parameters measured included broccoli height, number of leaves, leaf area, stem girth, and fresh weight of broccoli biomass. Leaf nutrient concentrations of broccoli were also determined. Data were subjected to analysis of variance, and significant means were separated using Duncan’s multiple range test at p  = 0.05. Results indicated that biochar-amended plots significantly improved soil physicochemical properties compared to the control. Biochar application also significantly increased broccoli height, number of leaves, leaf area, stem girth, leaf nutrient concentrations, and fresh weight of broccoli biomass. The application of tithonia biochar at rates of 10, 20, 30, and 40 t ha − 1 increased the fresh weight of broccoli biomass by 13%, 38%, 26%, and 23%, respectively, compared to the control. The application rate of 20 t ha − 1 was found to be the most beneficial, enhancing leaf nutrient concentrations and growth parameters. This study recommends the use of Tithonia diversifolia biochar as a soil amendment to improve soil quality of sandy loam and enhance broccoli productivity and quality.