Mir Zaman Hussain (1,2), Stephen K. Hamilton (1,2,3,4) and G. Philip Robertson(1,2,5)
1 W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI 49060, USA
2 Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, USA
3 Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA
4 Cary Institute of Ecosystem Studies, Millbrook, NY 12545, USA
5 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
Presented at the All Scientist Meeting and Investigators Field Tour (2021-09-23 to 2021-09-23 )
To sustain agricultural production, phosphorus (P) fertilizer inputs should counterbalance P outputs in crop harvest, overland runoff, and percolation out of the root zone. P surpluses resulting from excess P fertilization can cause eutrophication (e.g., harmful algal blooms) in water bodies. Between 2008 and 2019, we analyzed P inputs (added via fertilization and atmospheric P deposition) and outputs (P removal by harvest and leaching losses) of a corn-soybean-wheat crop rotation under tilled and no-till management. Although varying by year and crops, these cropping systems on average received 13 kg P ha-1 y-1. Soil test P (STP; 0-25 cm depth) was measured every autumn. Harvested biomass (grain and stover) was analyzed for P determination and P harvest removal was calculated from tissue concentration and harvest yield. Since P leaching was not measured in these systems, measured P leaching rates from nearby corn trials were added to the P budget. Fertilization and harvest P removal dominated the P budget, while atmospheric deposition and leaching were relatively insignificant in these cropping systems. Even though these cropping systems removed considerable P in harvest, P fertilization counterbalanced these losses and resulted in a positive P balance toward the end of the study period. The mean annual positive changes in P balance for these cropping systems under tilled and no-till agriculture were 6.3 and 4.8 kg P ha-1 yr-1, respectively. Despite an apparent positive P balance, STP did not show a detectable trend, and remained above the agronomic P optimum. This study shows how P fertilization can be calibrated to counterbalance harvest losses with relatively little P lost or gained by other pathways, at least under the favorable circumstances of nearly no erosion and overland flow off the study fields.
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