Nutrient Dynamics and Partitioning in Soybean.

Nutrient balance in soybean [Glycine max (L.) Merr.] is required since yield is limited due to nutrient deficiencies. Hence, a better understanding of nutrient dynamics and partitioning is important to perform accurate management practices in this topic. This study explores in the first place, the relationship of nitrogen (N) and seed yield and its variation through changes in two main components in N dynamic: N harvest index (NHI) and N grain concentration (%N_seed). Furthermore, relationship between NHI, phosphorus (P), and potassium (K) harvest index with harvest index (HI) were analyzed to explore different responses in each nutrient to variation in biomass partitioning. A metadata set was gathered (n=166) from different combination of environments, genotypes and management practices from Indiana (IN), Kansas (KS) and Argentina (ARG). The relationship between seed yield and plant N uptake was primarily affected through changes in NHI rather than %N_seed, with the latter acting as a more conservative variable. Both, NHI and PHI, showed a similar trend in the response to changes in HI with the exception of KHI. These relationships were explained through changes of nutrient concentration in plant fractions (seed and stover). The stoichiometry of the crop analyzed through the changes of N:P and N:K ratios was closely accounted for by changes in stover rather than in seed nutrient concentrations. Nutrient partitioning and dynamic in the plant are accounted for changes in nutrients concentration at reproductive and vegetative organs. These results also emphasize the fact that increasing seeds yields and HI must be complemented with improvements in the aptitude of plants for nutrient uptake, remobilization/utilization.