Is your soil low in iron and/or alkaline? That's usually the reason for using the sulfur and iron. Sulfur helps acidify the soil and plants have a difficult time using iron even if it's in the soil if the pH is too high. I don't know what Amine Salt and Mecropop are. Do you know whether your soil is low in P and K (phosphorous and potassium)? If you don't need the P and K, you don't need Fertilizer 2. If you need P and K, that's the only one that seems to have them, so that would be the one to use. If you have iron, but the soil is too acidic, I would use either fertilizer 1 or 2, depending on whether you need the P and K or not. If your pH is not too high, but your soil is low in iron, I'd use Fertilizer 3. If you need the iron and the P and K, I'd use 2 for some feedings and 3 for others.

I did years ago, using them in a fertilizer injector tied into my watering system. I used a very dilute mixture of mostly 46-0-0 urea. My main fertilizer though was organic to help the soil. I now use only organic fertilizers in the garden. Retirement gave me the time. When I worked and was time deficient, I applied fertilizer the easiest way possible. The 50 gallon cans and trash pumps were used for applying alfalfa tea to the individual bushes rather than attempting to haul it in buskets. I still use very dilute water solubles when I overhead water the plants in my greenhouse. That's the most effecient way to fertilize all those potted plants. Changing circumstances call for different methods to be used as I get older.

Soil Fertility Some Average Values and misc PPM based on the dry weight of the loam soil Sp=1.42 (Sp=1 is about 62.4lb/cuft or 1000grams/Liter(1000 cubic cm ). Low- N: 0-20, P: 0-12, K: 0-50 Med- N: 20-50, P: 12-25,K : 50-100 High- N: above 50, P: over 25, K : over 100 Note: Actual amounts of the nutrient is based the reference used for the PPM calculations. Example the 100ppm in a water solution is less than 100ppm in loam soil. The loam amount is 1.42 times more than the water. “Sp” is the ratio of the weight of an equal volumes of a substance compared to water. Sp Water 1.0, Sandy Loam 1.47, Loam 1.42, UC Mix Potting Soil 0.24, and PeatMoss 0.1 Misc Note: On a Fertilizer Bag the middle number is the percentage per weight of P2O5 in the fertilizer. The actual P amount is about 0.437 this value. This was calculated from a periodic table using the atomic weights of Phosphorus and Oxygen. The Phosphorous being about 43.7% of the total weight of the compound. The same for K2O, K is about 83% of the total compound weight. Example 100ppm Nitrogen in water is 100 mg N per Liter, but 147 mg N in a liter of Sandy Loam soil. For water 1ppm is a 1mg/Liter. Correction on the Previous MG Potting Soil Calculation: Bag Label Info 2.25cuft (63.71 liters) net weight 29.25lbs (13.26 kg) Density 13.26/63.71= 0.208g/ml or cubic cm Sp is approx 0.21 Nutrients N 0.21% P2O5 0.11% K2O 0.16% 6 month release Total Nitrogen in a liter mix is 1000grams *Sp mix*.21%N= 1000*0.21*(0.21/100)= 0.441grams N per Liter ( 441ppm N total, 73.5ppm monthly@ Sp1 reference) Duplicating using 6mo Osmocote Plus 15% N is 0.441 g/0.15= 2.94g/Liter approx heaping 1/2tsp. Just under the 1TBS CRF per Gallon of Mix recommended in Gritty Mix Recipe.

finally.. a box to type in .... first.. i would contact your county Ag or extension office.. and have a soil test done .... this is the primary place to start with figuring out if in fact.. your soil needs anything ... moss can be an indication of a nutrient poor soil ... and if your soil is that depleted.. a little foliar fert isnt going to do much ... next.. i went thru exactly what you are thinking about with a cheap sprayer ... bottom line ... the applicator you have is devoid of any science ... and there is no way to predict the amounts fed out ... to get a machine with that precision ... you would be shopping the the horticultural trade vendors.. and probably spending hundreds.. if not thousands for a precision applicator ... so then you would be down to trying to use a search engine ... and find out how much to put in your gizmo ... and just winging it... with the primary focus on ... you can always repeat a light application in a month .. but you will be hard pressed to revive a plant you burned the heck out of with to strong an amount ... i am not one to think that fert is a remedy for much of anything .... in fact.. i gave up using it long ago ... which leads me to wonder about your project .. and what other variables are a problem ... and how you might fix them .... the following variables come to mind: 1) if grass was hard to grow ... how much sun is available .... many thing will grow in shade ... but i might be hard to get things established and thriving in low sun .... not enough light .. to grow the roots they need to thrive... 2) if grass wont grow.. are the trees sucking away all available water and some of the plants are suffering or failing.. are you watering individual plants.. causing the tree roots to invade the planting hole ... rather than broadcasting water ... 3) and finally ... if you pant a hundred plants.. it isnt surprising to lose some ... its simply the odds ... fert will not fix any of those variables ... all that said.. you dont mention what kind of ivy .... but many of them root rather easily ... and you might be able to root some sprigs from the better plants... and have some to plant in fall .... fill in the holes ... good luck ken