Compost magnesium

Procedure. Carry out the extraction and then determine phosphorus as in Method 5.9a, except that working standard solutions should be made up in the Mehlich 1 extractant. Determine potassium and magnesium as in Method 5.10, except that standards are made up in Mehlich 1 extractant. Determine calcium as in Method 5.2, except that standards are made up in Mehlich 1 extractant. The composition of composts is so variable that appropriate dilutions of extracts may be required, and calculations adjusted accordingly. 

Sufficient quantities of phosphorus (P), potassium (K) and magnesium (Mg) are usually added to the soil along with organic material (compost or manure). The deliberate addition of these minerals is only advisable if there is some evidence of deficiency or if supply levels are in categories A, B or C (low, moderate or sufficient). 

Celery is a heavy feeder. Boron deficiency causes brown, mottled leaves and horizontal cracks on stalks. Florida 683 is tolerant of low boron. Calcium deficiency causes the center of the plant to blacken and die. Utah 52-70R Improved is tolerant of low calcium. Magnesium deficiency causes yellow leaves. Discolored streaks on stalks are a symptom of potassium deficiency. Phosphorus deficiency causes plants to form rosettes. Prevent problems by adding plenty of compost to the soil and by spraying plants with seaweed extract every 2 weeks. Check suspected deficiencies with soil tests and amend soil as needed. 

Cause Scab. This fungal disease is a problem in dry soil when pH is high and magnesium is low. Keep soil moist and maintain a pH below 6.5. Spray foliage with Epsom salts (1 tablespoon per gallon of water) or side-dress with compost to add magnesium. 

Odors that form in composting bins can be controlled using magnesium peroxide, as well as supplying oxygen to the aerobic bacteria, which can speed up the composting process. 

Compost quality No negative effects on density, total dry solids, volatile solids, salt content, pH, total nitrogen, ammonium nitrogen, phosphorus, magnesium and potassium eco-toxicity effects on 2 crop plants. 

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