Data from: Temporal dynamics of nutrient uptake by neighboring plant species: evidence from intercropping

The productivity of species-diverse plant assemblages strongly depends on the temporal dynamics of nutrient uptake by competing neighbouring plants. Our understanding, however, of how rates of nitrogen (N), phosphorous (P) and potassium (K) uptake might change through time between neighbouring plant species under field conditions is still very limited.
Here, we specifically measure the temporal trajectories of N, P and K uptake by staple food plants such as wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and maize (Zea mays L.) when growing either in monocultures or in intercropping systems. We ask how (i) plant species combinations, (ii) N fertilization and (iii) film mulching might affect key indexes of N, P and K uptake over time. We fit logistic models to characterize the nutrient uptake trajectories.
Maximum cumulative N, P and K uptake (kg ha−1) by wheat and barley were significantly greater in wheat–maize or barley–maize intercropping systems than in wheat or barley monocultures. Cumulative nutrient uptake by intercropped maize (either with wheat or with barley) was reduced by interspecific competition at early growth stages, but it increased rapidly after wheat and barley were harvested. Maximum cumulative N and P (but not K) uptake by intercropped maize were significantly higher than the uptake by monoculture maize, particularly when N fertilizer or film mulching was applied.
Intercropping induced a significant temporal niche differentiation in maximum daily nutrient uptake rates (kg ha−1 day−1) between intercropped species. Fertilization had much stronger effects on maximum cumulative nutrient uptake of maize than that of wheat and barley. Mulching significantly increased the maximum cumulative nutrient uptake of maize and advanced the time to reach its maximum daily P and K uptake rates.
Our study provides evidence of an important temporal niche differentiation mechanism (‘temporal complementarity’) in nutrient uptake rates between neighbouring plant species. A better understanding of temporal trajectories of interspecific nutrient uptake rates remains crucial if we want to maximize the nutrient-use efficiency and sustain overyielding (i.e. high food production) in plant species-diverse systems such as intercropping.

物种多样的植物群落的生产力，在很大程度上取决于竞争邻株的养分吸收时间动态。然而，我们对于田间条件下邻株物种间氮(N)、磷(P)和钾(K)吸收速率随时间的变化规律，认知仍十分有限。

本研究专门测定了小麦（Triticum aestivum L.）、大麦（Hordeum vulgare L.）和玉米（Zea mays L.）等主食作物，在单作或间作系统中生长时，氮、磷、钾吸收的时间轨迹。我们旨在探究三个问题：(i) 植物物种组合、(ii) 氮肥施用以及(iii) 地膜覆盖，如何随时间影响氮、磷、钾吸收的关键指标。我们通过拟合逻辑斯蒂模型以表征养分吸收轨迹。

小麦与大麦在小麦-玉米或大麦-玉米间作系统中的最大累积氮、磷、钾吸收量（kg ha⁻¹），显著高于其单作时的水平。间作玉米（与小麦或大麦间作）的累积养分吸收量在生长早期会因种间竞争而降低，但在小麦和大麦收获后会迅速提升。间作玉米的最大累积氮、磷（而非钾）吸收量显著高于单作玉米，尤其在施用氮肥或地膜覆盖的情况下。

间作使间作物种间的最大日养分吸收速率（kg ha⁻¹ day⁻¹）出现了显著的时间生态位分化。施肥对玉米最大累积养分吸收量的影响远强于对小麦和大麦的影响。地膜覆盖显著提升了玉米的最大累积养分吸收量，并提前了其达到最大日磷、钾吸收速率的时间。

本研究为邻株物种间养分吸收速率存在重要的时间生态位分化机制（即"时间互补性"）提供了实证依据。若要最大化植物多样系统（如间作系统）的养分利用效率并维持超产效应（即高产），进一步明晰种间养分吸收速率的时间轨迹仍至关重要。