Corn Stover Removal Responses on Soil Test P and K Levels in Coastal Plain Ultisols

Jeffrey M Novak,Thomas F Ducey,James R Frederick,Douglas L Karlen,Don W Watts

doi:10.3390/su13084401

Abstract

Corn (Zea mays L.) stover is used as a biofuel feedstock in the U.S. Selection of stover harvest rates for soils is problematic, however, because excessive stover removal may have consequences on plant available P and K concentrations. Our objective was to quantify stover harvest impacts on topsoil P and K contents in the southeastern U.S. Coastal Plain Ultisols. Five stover harvest rates (0, 25, 50, 75 and 100% by wt) were removed for five years from replicated plots. Grain and stover mass with P and K concentration data were used to calculate nutrient removal. Mehlich 1 (M1)-extractable P and K concentrations were used to monitor changes within the soils. Grain alone removed 13–15 kg ha−1 P and 15–18 kg ha−1 K each year, resulting in a cumulative removal of 70 and 85 kg ha−1 or 77 and 37% of the P and K fertilizer application, respectively. Harvesting stover increased nutrient removal such that when combined with grain removed, a cumulative total of 95% of the applied P and 126% of fertilizer K were taken away. This caused M1 P and K levels to decline significantly in the first year and even with annual fertilization to remain relatively static thereafter. For these Ultisols, we conclude that P and K fertilizer recommendations should be fine-tuned for P and K removed with grain and stover harvesting and that stover harvest of >50% by weight will significantly decrease soil test M1 P and K contents.

Highlights

Fertilizer application (∑ 225 kg K; 2008 to 2012). These P and K removals are similar to those reported by Karlen [28] for what they defined as moderate (~50%) and high (~90%) harvest rates. These results suggest that harvesting grain and stover from Coastal Plain soils will require a reevaluation of fertilizer recommendations since their combined nutrient removal totals caused a lowering of Mehlich 1 (M1)-extractable P and K concentrations
Research evaluating corn stover harvest for biofuel production has been a cyclic quest for over forty years, yet stakeholders still requested information on sustainable harvest levels to prevent soil quality degradation [45]. This information is especially germane for sustainable biofuel production using stover harvested from corn grown in nutrientimpoverish sandy Coastal Plain South Carolina Ultisols
This study focused on changes in M1-extractable P and K concentrations as affected by grain and stover harvest amounts

Summary

Introduction

Harvesting corn stover (cobs, stems, leaves, and husks) following grain harvest for use as cellulosic feedstock to produce bioenergy or other bio-based products has received considerable attention for the past twenty years. Recognized as a countermeasure to help mitigate increasing atmospheric CO2 concentrations [1,2] and to off-set ever-growing global consumption of petroleum [3] for liquid fuels, sustainability of harvesting stover has been extensively studied. Ethanol and other organic alcohols (i.e., butanol, etc.) can be created by processing corn grain, sugarcane (Saccharum officinarum), algae and various other lignocellulosic feedstocks [4,5]. Gas, liquid, and solid fuel phase forms of bioenergy can be produced from biomass using thermochemical conversion platforms such as co-firing, gasification, and both slow and fast pyrolysis [6,7]

Objectives

Methods

Results

Conclusion