with other crops, such as forages, results from turfgrass fertility studies not designed to relate to soil testing, and the best judgement of the agronomist making the recommendations.” Turner & Waddington, 1978
P and K requirement category … This decision was based on economics, not agronomics. The cost of fertilization was not considered of primary importance for turf.” Carrow et al., 20014 4Carrow, R.N., Waddington, D.V., and P.E. Rieke. 2001. Turfgrass Soil Fertility and Chemical Problems. Wiley. p. 164.
P fertilization recommendations is scant, and additional data is needed. Many current recommendations for P fertilizer for turfgrasses are based on forage- or ﬁeld-crop calibration data.” Frank & Guertal, 20135 5Frank, K.W. and E.A. Guertal. 2013. Potassium and phosphorus research in turfgrass. In: Stier, J.C., B.P. Horgan, and S.A. Bonos, editors, Turfgrass: Biology, Use, and Management, Agron. Monogr. 56. ASA, CSSA, SSSA, Madison, WI. p. 493-519.
tend to ﬁnd that the levels required are lower than what we previously thought – meaning that ‘low potassium’ you got on your last soil test report might be optimum down the road.” Doug Soldat in “How reliable is soil testing?” (2013)
Levels for Sustainable Nutrition [MLSN] guidelines ... the minimum levels published by PACE are drastically lower than many traditional soil test interpretations, and likely more accurate.” Doug Soldat in “How reliable is soil testing?” (2013)
of plant use. • b is the amount we want to ensure remains in the soil after the plant use is accounted for. This is a minimum we don’t want to drop below. You can think of it as a reserve amount in the soil. This is the MLSN guideline level. • c is the amount actually present in the soil. This is the soil test result.
required as fertilizer as Q. a + b − c = Q where, a is the quantity of the element used by the grass b is the quantity of the element kept in the soil c is the quantity of the element present in the soil Q is the quantity of the element required as fertilizer