|Novak, Jeffrey - Jeff|
|Hunt, P - Retired ARS Employee|
|Glaz, Barry - Retired ARS Employee|
|Watts, Donald - Don|
|Cantrell, K - Collaborator|
|Busscher, W - Retired ARS Employee|
Submitted to: Water, Air, and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2014
Publication Date: 12/11/2014
Citation: Novak, J.M., Sigua, G.C., Spokas, K.A., Hunt, P.G., Glaz, B.S., Watts, D.W., Cantrell, K.B., Busscher, W.J. 2014. Plant macro- and micronutrient dynamics in a biochar-amended wetland muck. Water, Air, and Soil Pollution. Doi 10.1007/s11270-014-2228-y.
Interpretive Summary: Histosols in the Florida everglades are Organic Matter (OM)-rich muck soils that formed over hundreds of years in a limestone-basin from saw grass and marsh plant residue accumulation. These Histosols were drained over the past 100 years for growing crops. Draining them has increased oxidation of the OM-rich muck resulting in severe reductions in soil thickness. For example, the Histosols were initially several feet thick in areas, but more recently some are only a few feet thick. The long-term sustainability of crop production in the Everglades will be a challenge because nearly one-half of the south Florida Everglades Histosols will have their thickness reduced to < 1 foot. Biochar application to the Histosols has been offered as a possible management option to prolong the sustainability of crop production. Biochar is the solid byproduct produced during pyrolysis of plant residue materials and animal manures for biofuel production. We conducted an experiment whereby biochars produced from plant residue and animal manure were mixed into a Florida Histosol and were laboratory incubated for four months. The samples were leached with water about every month and analyzed for leached nutrients. At the end of the experiment, the soils were extracted for estimates of plant available nutrients. We discovered that the plant based biochar did not substantially improve the fertility of the Histosols or released nutrients into the water leachates. Biochar produced from animal manure, however, released substantial concentrations of phosphorus and potassium. We conclude that plant-based biochars did not cause large fertility improvements, but manure based biochars did release nutrients into the Histosol and water leachates.
Technical Abstract: Drainage of Histosols (mucks) in the Florida Everglades Agricultural Area (EAA) has resulted in extensive subsidence. Decreases in profile thickness threatens long-term agricultural sustainability of the EAA. We hypothesized that biochars could bolster sustainability of these mucks by rebuilding their organic carbon (OC) pool and fertility levels. Two biochars were produced by pyrolysis at 350° Celcius from pine chips (Pinus taeda) and swine solids (Sus scrofa domesticus). They were mixed into triplicate pots containing a Lauderhill muck (Euic, hyperthermic Lithic Haplosaprist) at 0, 2.5, 5 and 10 gram/100 gram (g) (dry weight). During 124 day incubation, pots were leached four times with deionized water. At the end of the incubations, the muck’s fertility characteristics were assessed, and leachates were analyzed for dissolved organic carbon (DOC), dissolved Potassium (DK) and dissolved Phosphorus (DP). Neither biochars significantly increased the mucks total combustible nitrogen (TCN) or its OC contents. Swine solid biochar at all three applications rates significantly increased Mehlich 1 extractable potassium, phosphorus, magnesium, and sodium. Pine chip biochar added at 10 g/100 g only improved the Mehlich 1 extractable potassium concentration. Water leachates from muck soil treated with swine solid biochar had significantly higher DP concentrations. Both biochars significantly increased cumulative DOC concentrations relative to the control. On one hand, DP released by swine solid biochar has the potential to cause water quality issues. On the other hand, pine chip biochar may be a unsuitable amendment for Histosols in the EAA because the most DOC released occurred in soils treated with 10 g/100 g pine chip biochar.