soil fertility final exam

critical level

soil test level below which crops likely respond to added nutrients, or soil test level above which crops likely to not respond to added nutrients

relative yield

(actual yield/theoretical yield) x 100

PI, KI limit

50

ZnI, CuI, MuI, SI limit

25

soil testing - fertilizer recommendation system

soil sampling, soil analysis, interpret soil test results, provide nutrient recommendations

How to calculate waste rate needed to meet a crop N requirement

% N crop= (lb/100lb)(2000/t)=(lb N crop/t)

(t/ac)(lb N crop/t)=(lb N crop/a)(10^6lb wet/total N from report lb)(Tw/2000)=(Tw/a)(1 lb Nt/0.5lb NA)

How to calculate lbs P2O5/Tw of waste

(lb P/10^6 lb dry)(2000lb/t)=(lb P/t dry)(2.29/1)=

(lb P2O5/t dry)(DM% lb dry/1 lb wet)=lb P2O5/T wet

How to calculate lbs of P2O5/a applied in excess

(waste rate gal/a)(P2O5 avail 1st yr/1000)=(lb P2O5/a applied)

(t/a)(2000lb/t)(% P)=(lb P/a)(2.29)=lb P2O5/a

(lb P2O5/a applied)-(lb P2O5/a)= lb P2O5/a excess

How to calculate yrs to meet limit

2ppm-->20ppm= +18ppm x 10 =180ppm/49.3=3.65 yrs