Building soil fertility using soil amendments

Soil amendments are organic and inorganic materials added to soil to improve it quality and chemistry for plants growth. Slag amendment is a material rich in silicon produced from manufactured steel. Effective utilization of organic amendments and slag builds soil fertility, improves plants resistance against disease, and it is important for sustainable agriculture. Greenhouse studies conducted at Rutgers University Vegetable Research Farm in East Brunswick, New Jersey from January 2013 to January 2014, compared various soil amendments for: (i) their ability to supply silicon for plants uptake, (ii) ability to suppress powdery mildew disease in pumpkin, and (iii) ability to neutralize soil acidity and raise soil pH. Sassafras siliceous, mesic, typical Hapludult sandy loam soil initial pH 5.1 was used to fill 2 gallon pots planted to pumpkin (Cucurbita pepo.). The soil was not amended for the control but amended with different types of soil amendments as liming materials. The amendments compared included agricultural limestone (calcite & dolomite), Calcium Magnesium Silicate (Agrowsil from Harsco Minerals), Calcium Silicate (Wollastonite from R.T. Vanderbilt), Montana Grow, Glacier Rock Flour, Wood ash, Compost, and Cereal Rye/ Hairy Vetch cover crop. At the conclusion of the greenhouse experiment, some soil amendments were effective as liming materials and others had little effect on soil chemical properties. Calcite and dolomite, common agricultural liming materials increased soil pH by one fold than unamended and exchangeable Ca and Mg. Of the various non-carbonate amendments, CaMgSilicate (Agrowsil), Calcium Silicate (Wollastonite), and wood ash significantly increased soil pH similar to calcite and dolomite. CaMgSilicate and calcium silicate amendments increased Soil test extractable Si levels by tenfold over unamended soil, calcite and dolomite. Si concentration in rye tissue was higher in CaMgSilicate plots (3.7 g/kg) than limestone plots (2.7 g/kg). Silicon level in pumpkin tissue was higher in calcium silicate (6575 mg kg-1) than CaMgSilicate (4000 mg kg-1). Calcium silicate delayed the onset of powdery mildew disease by 20 fold more than all amendments. The study found that calcium silicate and wood ash could be a useful alternative for limestone and calcium silicate may help protect pumpkin crops against disease.M.S.Includes bibliographical referencesby J. Lepolu Torlo