Maize Performance in Relation to Soil Compost Rates and Soil Health Test Factors.

It is challenging to predict the performance of maize based on soil tests and properties of compost amendments. Our study employed two different types of compost (biosolids vs leaves) applied at 3 rates to hybrid sweet corn.  Soil plots were uniform except two plots intercepted a long-term sod plow-down. A suite of soil tests considered potentially predictive of performance included available inorganic-N, 7-day anaerobic N-min, water-extractable organic carbon (WEOC), water extractable organic-N (WEON), Solvita Labile-Amino-N (SLAN) and PSNT assessed at knee-high corn. We also measured soil carbon dioxide (CO₂) respiration using a drying-rewetting CO2-burst procedure on soils before, during and after the growing season.  Both types of compost amendment had positive yield effects and also showed carry-over effects the 2nd year, when the field was split.  These trials show composts will provide significant fertilizer value at practical rates, increading yield and N-uptake over control plots. Biologically oriented soil tests not normally used to predict crop response showed good correlations with each other. A SLAN test which assessed amino-N pools gave a r2 of 78% to N-uptake, and predicted the effect of sod-plow down from two plots that was not predicted by other tests. Therefore SLAN may be a useful cover crop soil health test. PSNT tests in July correlated well with yield and provided reassurance of meeting yield goals but would be impractical for growers using manure or compost amendments.  A variety of novel soil tests that relate to soil health provided meaningful results aiding in understanding and predicting maize performane on a Maine soil.