Please define organic where using superphosphate is concerned. Also when using 10-10-10. Thank you.
Superphosphate is a synthetic chemical fertilizer that is not approved for use in organic agriculture. It is manufactured by treating mined phosphate rock with sulfuric acid. It’s toxic to the microbial life of your soil. Because it’s water soluble, it can also contribute to phosphorus pollution of waterways.
If your garden soil lacks phosphorus, it’s better to apply it in the form of bone meal, rock phosphate, composted poultry manure, or compost made from yard waste and kitchen scraps. These organic materials release phosphorus to the soil slowly as they are broken down by soil bacteria. Fish emulsion and liquid seaweed fertilizers offer a quick phosphorus boost.
The ratio 10-10-10 describes the quantities of nutrients within a fertilizer but doesn’t reveal whether or not it’s organic. That said, the vast majority of fertilizers with a 10-10-10 analysis are synthetic. The three numbers represent the percentages of available nitrogen, phosphorus, and potassium in the fertilizer.
Gardeners who are in the habit of regularly feeding their soil with rich compost often find that they have no need for additional fertilizers. If necessary, you can supplement compost with complete organic fertilizers that blend natural sources of nitrogen, phosphorus, and potassium, as well as micronutrients such as iron and calcium. You’ll know which products at the garden center are organic by their “OMRI Listed” label. —Doug Hall
My order of 50 bareroot strawberry plants will arrive at the end of April. The supplier recommends mixing 10-10-10 chemical fertilizer into the soil. Can you suggest an organic alternative? I have some horse manure, but it doesn’t appear to be fully rotted to use at this time.
Strawberries grow best where the soil is fertile, well-drained, and amply enriched with organic matter. If you have been using compost, organic mulches, and cover crops in your garden for several years, you may need to do nothing further before planting the strawberries. A soil test will give you an accurate reading of how fertile your soil is.
If your soil falls short of the ideal, I recommend you dig in some organic amendments before you plant. Composted horse or steer manure is excellent for this purpose; it’s sufficiently composted when it looks and smells like soil. Yard-waste compost is another good source of nutrients and organic matter. Sphagnum peat moss as a soil amendment adds organic matter but little in the way of nutrients. Ideally, you should prepare the soil a few weeks before planting the strawberries.
Water thoroughly after planting, then give each plant one cup of a half-strength fish emulsion solution or compost tea to jump-start growth. Follow up 3 weeks later with another application if growth is slow.
Let your supply of fresh horse manure decompose longer before using it. You can layer it with leaves, kitchen scraps, and other garden debris to make compost, if you wish, or simply let it age in a pile. Next spring, use it to top-dress the strawberry bed when the plants begin to bloom. —Doug Hall