Maize growth, organ development, and yield formation are highly controlled by the manner in which the plant captures, partition, and remobilizes biomass and phosphorus (P). Better understanding of biomass and P accumulation, partition, and remobilization processes will improve modeling of crop resource use. However, there is still a lack of detailed data to parameterize the modeling of these processes, particularly for modern maize cultivars. A two-year (2016 and 2017) field experiment with three P fertilization treatments (0 (P0), 75 (P75), and 300 (P300) kg P2O5 ha−1) was conducted on a Fluvo-aquic soil (Quzhou, Hebei province, China) to collect data and quantify key processes for a representative modern maize cultivar (Zhengdan 958) widely grown in China. The proportions of biomass and P partitioned into various maize organs were unaffected by P application rate. Zhengdan 958 showed a much lower leaf-senescence rate than older cultivars, resulting in post-silking leaf photosynthesis being sufficient to meet grain biomass demand. In contrast, 50%–85% of leaf P and 15%–50% of stem P accumulated pre-silking were remobilized into grain, in spite of the large proportion of post-silking P uptake. Our results are consistent with the theory that plants use resources according to the priority order of re-allocation from senescence followed by assimilation and uptake, with the re-translocation of reserves last. The results also enabled us to estimate the threshold P concentrations of Zhengdan 958 for modeling crop P demand. The critical leaf P concentration for individual leaves was 0.25%–0.30%, with a corresponding specific leaf P (SLP) of 75–100 mg P m−2. The structural P concentration for leaf was 0.01%, corresponding to an SLP of 3.8 mg P m−2. The maximum P concentrations of leaves and stems were 0.33% and 0.29%. The residual P concentration for stems was 0.006%.
