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Crop-livestock production systems are the largest cause of human alteration of the global nitrogen (N) and phosphorus (P) cycles. Our comprehensive spatially explicit inventory of N and P budgets in livestock and crop production systems shows that in the beginning of the 20th century, nutrient budgets were either balanced or surpluses were small; between 1900 and 1950, global soil N surplus almost doubled to 36 trillion grams (Tg)·y −1 and P surplus increased by a factor of 8 to 2 Tg·y −1 . Between 1950 and 2000, the global surplus increased to 138 Tg·y −1 of N and 11 Tg·y −1 of P. Most surplus N is an environmental loss; surplus P is lost by runoff or accumulates as residual soil P. The International Assessment of Agricultural Knowledge, Science, and Technology for Development scenario portrays a world with a further increasing global crop (+82% for 2000–2050) and livestock production (+115%); despite rapidly increasing recovery in crop (+35% N recovery and +6% P recovery) and livestock (+35% N and P recovery) production, global nutrient surpluses continue to increase (+23% N and +54% P), and in this period, surpluses also increase in Africa (+49% N and +236% P) and Latin America (+75% N and +120% P). Alternative management of livestock production systems shows that combinations of intensification, better integration of animal manure in crop production, and matching N and P supply to livestock requirements can effectively reduce nutrient flows. A shift in human diets, with poultry or pork replacing beef, can reduce nutrient flows in countries with intensive ruminant production.

Spatial predictions of soil macro and micro-nutrient content across Sub-Saharan Africa at 250 m spatial resolution and for 0–30 cm depth interval are presented. Predictions were produced for 15 target nutrients: organic carbon (C) and total (organic) nitrogen (N), total phosphorus (P), and extractable—phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), sodium (Na), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), aluminum (Al) and boron (B). Model training was performed using soil samples from ca. 59,000 locations (a compilation of soil samples from the AfSIS, EthioSIS, One Acre Fund, VitalSigns and legacy soil data) and an extensive stack of remote sensing covariates in addition to landform, lithologic and land cover maps. An ensemble model was then created for each nutrient from two machine learning algorithms—random forest and gradient boosting, as implemented in R packages ranger and xgboost—and then used to generate predictions in a fully-optimized computing system. Cross-validation revealed that apart from S, P and B, significant models can be produced for most targeted nutrients (R-square between 40–85%). Further comparison with OFRA field trial database shows that soil nutrients are indeed critical for agricultural development, with Mn, Zn, Al, B and Na, appearing as the most important nutrients for predicting crop yield. A limiting factor for mapping nutrients using the existing point data in Africa appears to be (1) the high spatial clustering of sampling locations, and (2) missing more detailed parent material/geological maps. Logical steps towards improving prediction accuracies include: further collection of input (training) point samples, further harmonization of measurement methods, addition of more detailed covariates specific to Africa, and implementation of a full spatio-temporal statistical modeling framework.

Nutrient limitation to primary productivity and other biological processes is widespread in terrestrial ecosystems, and nitrogen (N) and phosphorus (P) are the most common limiting elements, both individually and in combination. Mechanisms that drive P limitation, and their interactions with the N cycle, have received less attention than mechanisms causing N limitation. We identify and discuss six mechanisms that could drive P limitation in terrestrial ecosystems. The best known of these is depletion-driven limitation, in which accumulated P losses during long-term soil and ecosystem development contribute to what Walker and Syers termed a \"terminal steady state\" of profound P depletion and limitation. The other mechanisms are soil barriers that prevent access to P; transactional limitation, in which weathering of P-containing minerals does not keep pace with the supply of other resources; low-P parent materials; P sinks; and anthropogenic changes that increase the supply of other resources (often N) relative to P. We distinguish proximate nutrient limitation (which occurs where additions of a nutrient stimulate biological processes, especially productivity) from ultimate nutrient limitation (where additions of a nutrient can transform ecosystems). Of the mechanisms that drive P limitation, we suggest that depletion, soil barriers, and low-P parent material often cause ultimate limitation because they control the ecosystem mass balance of P. Similarly, demand-independent losses and constraints to N fixation can control the ecosystem-level mass balance of N and cause it to be an ultimate limiting nutrient.

Nitrogen (N), phosphorus (P), and potassium (K) fertilization is widely used to enhance crop productivity. However, the synergistic effects of combined N, P, and K application on sweetpotato yield and nutrient use efficiency are not fully understood. To address this knowledge gap, a field experiment was conducted with five treatments: control (CK), no N (-N), no P (-P), no K (-K), and full NPK application (NPK). We systematically analyzed storage root yield, yield components, and nutrient accumulation characteristics. Additionally, fertilizer use efficiency and soil nutrient balance were evaluated. The NPK treatment significantly increased storage root yield by 34.8–53.1% compared with single nutrient deficiency treatments. The greatest yield reduction was observed under -P conditions, associated with low soil available P and a disordered N and K allocation ratio (5.10–14.40%). Phosphorus application resulted in high agronomic efficiency (187.79 kg kg −1 P 2 O 5 ) but low recovery efficiency (0.05–0.25 kg kg −1 P 2 O 5 ), whereas -N and -K treatments led to soil P surplus (50.25–63.06 kg ha −1 ). A logistic model revealed that NPK treatment increased the maximum and average nutrient accumulation rates compared with deficient treatments. Pearson correlation analysis showed significant positive relationships between yield and yield components, as well as nutrient accumulation in storage roots and whole plants. Random forest regression identified P accumulation in storage roots as the most important predictor of yield. In conclusion, combined NPK fertilization enhances both storage root yield and nutrient use efficiency, with targeted P management playing a critical role in achieving high-yield and high-efficiency sweetpotato production.

Inspired by previous studies that have indicated consistent or even well-constrained (relatively low variability) relations among carbon (C), nitrogen (N) and phosphorus (P) in soils, we have endeavored to explore general soil C:N:P ratios in China on a national scale, as well as the changing patterns of these ratios with soil depth, developmental stages and climate; we also attempted to determine if well-constrained C: N:P stoichiometrical ratios exist in China's soil. Based on an inventory data set of 2,384 soil profiles, our analysis indicated that the mean C:N, C:P and N:P ratios for the entire soil depth (as deep as 250 cm for some soil profiles) in China were 11.9, 61 and 5.2, respectively, showing a C: N: P ratio of ~ 60: 5:1. C:N ratios showed relatively small variation among different climatic zones, soil orders, soil depth and weathering stages, while C:P and N:P ratios showed a high spatial heterogeneity and large variations in different climatic zones, soil orders, soil depth and weathering stages. No well-constrained C:N:P ratios were found for the entire soil depth in China. However, for the 0-10 cm organic-rich soil, which has the most active organism-environment interaction, we found a well-constrained C:N ratio (14.4, molar ratio) and relatively consistent C:P (136) and N: P (9.3) ratios, with a general C:N:P ratio of 134:9:1. Finally, we suggested that soil C:N, C:P and N:P ratios in organic-rich topsoil could be a good indicator of soil nutrient status during soil development.

Aims The changes of nutrient limitation status for tree growth across a plantation chronosequence have great implications for plantation management. The underlying mechanisms for such a shift, however, have seldom been addressed. While plant nutrient use strategies would change in response to soil nutrient alteration, they may also create feedback on soil nutrient dynamics and thus plant nutrient limitation status. Methods We examined soil and foliar nutrients of larch (Larix kaempferi), the dominant timber species in Northeast China, across a plantation chronosequence. Results Total soil N increased but total soil P decreased across the chronosequence. Similarly, N concentrations in the green leaves were positively correlated, and P concentrations were negatively correlated with stand age. Foliar N:P ratios, N and P resorption efficiencies and PRE:NRE were positively correlated with stand age, indicating the shift from N-limitation to P-limitation across the chronosequence. P concentration in senesced leaves decreased and N:P ratios increased across the chronosequence, which has implications for decomposition and nutrient release. Conclusions Nutrient resorption, soil pH, biomass P sequestration and imbalanced inputs of N and P would contribute to the occurrence of P-limitation with increased stand age. Furthermore, adaptive fertilization management strategies should consider the shift of nutrient limitation patterns across the chronosequence.

• Community trait assembly in highly diverse tropical rainforests is still poorly understood. Based on more than a decade of field measurements in a biodiversity hotspot of southern Ecuador, we implemented plant trait variation and improved soil organic matter dynamics in a widely used dynamic vegetation model (the Lund-Potsdam-Jena General Ecosystem Simulator, LPJ-GUESS) to explore the main drivers of community assembly along an elevational gradient. • In the model used here (LPJ-GUESS-NTD, where NTD stands for nutrient-trait dynamics), each plant individual can possess different trait combinations, and the community trait composition emerges via ecological sorting. Further model developments include plant growth limitation by phosphorous (P) and mycorrhizal nutrient uptake. • The new model version reproduced the main observed community trait shift and related vegetation processes along the elevational gradient, but only if nutrient limitations to plant growth were activated. In turn, when traits were fixed, low productivity communities emerged due to reduced nutrient-use efficiency. Mycorrhizal nutrient uptake, when deactivated, reduced net primary production (NPP) by 61–72% along the gradient. • Our results strongly suggest that the elevational temperature gradient drives community assembly and ecosystem functioning indirectly through its effect on soil nutrient dynamics and vegetation traits. This illustrates the importance of considering these processes to yield realistic model predictions.

Well-designed temperate tree-based intercropping (TBI) systems can enhance soil nutrient cycling compared to conventional agricultural systems. To improve the TBI designs and their subsequent wide-scale adoption, greater understanding is required regarding the extent to which widely-spaced tree rows and tree management practices influence spatio–temporal dynamics of soil nutrients. Our 2-year study (2021 and 2022) assessed N-leaching and soil nutrient supply at increasing distances from tree rows (0, 4, 12, 20 m); the 10-year-old TBI system (50 trees ha −1 ) together with agricultural controls was established in southern Québec (Canada). The TBI included hybrid poplars (Populus deltoides  ×  P. nigra) planted alternately with high-value hardwoods in the rows. In each experimental block (n = 3), the TBI system and control were divided into two treatments: without root-pruning versus with (0.75 m depth using a sub-soiler). In 2022, NO 3 − supply rates near tree rows (0 and 4 m; 0.28 ± 0.04 [mean ± SE] and 0.37 ± 0.05 µg cm −2 d −1 , respectively) were lower than alley centres (12 and 20 m) and controls (0.62 ± 0.07, 0.52 ± 0.07 and 0.82 ± 0.07 µg cm −2 d −1 , respectively). A first structural equation modelling (SEM) analysis revealed that NO 3 − supply rates were mostly modulated by indirect effects of tree row distance and soil clay content through volumetric water content (VWC). Nitrate leaching (400-mm depth) at 0 and 4 m from the tree row was respectively 8.8 × and 7.5 × lower than that in the control. A second SEM analysis showed direct and indirect (through soil VWC affecting NO 3 − supply rates) effects of distance from tree rows on NO 3 − leaching rates. Within TBI, greater tree leaf litter dry-mass was trapped at 0 and 4 m versus 12 and 20 m. Phosphorus and K availability under tree rows was higher than all other distances within cultivated alleys and control plots. Phosphorus, K, Ca and Mg supplies within cultivated alleys were generally similar among distances (4, 12, and 20 m) and did not differ from controls. An unexpected lack of effect of tree root pruning was observed regarding soil nutrient supply and N leaching. Clay content was a major driver of soil nutrient supply and N leaching. The role of TBI systems in determining soil nutrient dynamics depended upon the soil nutrient and sampling period that was measured, with greater effects beneath the trees and at the tree-crop interface.

Aims The interaction between plants and soil is an important internal driver of ecosystem evolution. Many studies have reported the unidirectional effects of soil nutrients on plant diversity and species turnover. However, there are still many gaps in our knowledge about how plant diversity and species turnover feedback to soil nutrients. Methods In the present study, three forest plots with different species composition and diversity were created through artificial disturbance in the same stand origin forest, and their long-term dynamics were observed. We identified underlying mechanisms of how plant diversity (Shannon-Wiener index) and species turnover (Bray-Curtis dissimilarity) affect soil total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP). Results Plant diversity was associated with soil TN, TP, AN, and AP concentrations ( P  < 0.01). Species turnover was negatively correlated with the log-response ratio of TP ( LRR TP) ( P  < 0.001), but not correlated with LRR AP. Species turnover had significant positive correlations with LRR TN and LRR AN ( P  < 0.001). The structural equation model supports hypotheses that plant diversity and species turnover influenced soil N and P availability by affecting forest community growth (total tree basal area, TBA), litter quantity and quality, and soil physical and chemical properties (soil organic carbon, SOC; soil exchangeable base cations). Conclusions Collectively, our results highlighted the co-regulation of plant diversity and species turnover on soil N and P availability by “complementary” and “mass” effects during the long-term dynamics of forest ecosystems.

• Plant stoichiometric coupling among all elements is fundamental to maintaining growth-related ecosystem functions. However, our understanding of nutrient balance in response to global changes remains greatly limited to plant carbon : nitrogen : phosphorus (C : N : P) coupling. • Here we evaluated nine element stoichiometric variations with one meta-analysis of 112 global change experiments conducted across global terrestrial ecosystems and one synthesis over 1900 species observations along natural environment gradients across China. • We found that experimentally increased soil N and P respectively enhanced plant N : potassium (K), N : calcium (Ca) and N : magnesium (Mg), and P : K, P : Ca and P : Mg, and natural increases in soil N and P resulted in qualitatively similar responses. The ratios of N and P to base cations decreased both under experimental warming and with naturally increasing temperature. With decreasing precipitation, these ratios increased in experiments but decreased under natural environments. Based on these results, we propose a new stoichiometric framework in which all plant element contents and their coupling are not only affected by soil nutrient availability, but also by plant nutrient demand to maintain diverse functions under climate change. • This study offers new insights into understanding plant stoichiometric variations across a full set of mineral elements under global changes.