If you are growing an annual vegetable garden, having sufficient fertility is of paramount importance. Most people know that plants need nitrogen, phosphorus, and potassium to grow. These elements are represented on fertilizer bags everywhere in percentage terms by the three numbers prominently displayed. For example a 24-18-12 fertilizer has 24% nitrogen, 18% phosphorus, and 12 percent potassium. This is also an example of a chemical fertilizer. This I can tell simply because the percentages are too high for an organic fertilizer. An organic fertilizer rarely has more than a single digit percentage of any of the NPK ratio. There are also secondary elements and micronutrients that are often overlooked but still vital. For example, if you have a calcium deficiency you can apply all the NPK you want, but the plant will not be able to use it.
What Plants Crave: (These are the basics, but there are many more micronutrients needed)
The key to good fertility is diversity. There are many different techniques, manures, composts, and fertilizers to consider.
If you rotate your crops, you will have less nutrient deficiencies in the soil. Also, using heavy amounts of nitrogen fixing crops will boost fertility in depleted soil. (Peas, beans)
Composted manures are a fantastic way to build fertility in the garden. Cow, pig, rabbit, chicken, and horse manures are most common. It is important to compost the manures before adding to your garden, because of the possibility of pathogens, weed seeds, and burning plants. Having said that, rabbit pellets do not burn plants, and I have applied “hot” un-composted chicken manure in the late fall after the garden was finished without issue. I have also applied chicken manure during the season in fallow areas, with a layer of mulch to cover.
Manures can be very nutritious for your plants or they can be lacking vital nutrients. It really depends on the nutrition of the animal that the manure comes from. Ideally, your manures come from your own animals that have a nutritious varied diet free of chemicals. If you import manures, it is important to know what the animals were fed.
I prefer composts to manures, because it is has more ingredients, and is safer to apply. Manures are often an important component of compost, but it is usually mixed with other materials such as straw, leaves, grass, vegetable scraps, and wood chips. The variety of sources helps to insure that you are less likely to be missing valuable elements.
Fertilizing your plants with compost teas directly on the leaves of the plant can yield tremendous quick results. This can be a great addition to traditional compost, manures, and fertilizers. Compost teas improve growth by providing beneficial organisms that repel pests and improve nutrient retention in the soil. Teas also help to build soil life and improve biodiversity.
Wood mulch, leaf, straw, & living mulches such as nitrogen fixing clover add fertility to the soil, and protect soil life. It is vital to protect soil with a mulch of some kind.
Steve Solomon in Gardening when it Counts makes an excellent case for using what he calls a complete organic fertilizer. He describes a situation where he and his family were getting most of their nutrition from their garden. They ended up with some health problems relating to missing nutrients in his soil that ended up being deficient in the food they were eating. He also describes a neighbor’s family with health problems that uses only horse manure in his garden for fertility. This would probably never be noticed by most people, because most people don’t get the majority of their food out of their backyard. This struck a chord with me, because every year Denise and I get more and more calories out of our garden.
He swears by his complete organic fertilizer. He claims that your plants will grow like gangbusters, and the food will be highly nutritious and delicious. The recipe is as follows:
3 parts seed meal (flaxseed meal, alfalfa meal, soybean meal, cottonseed meal, rapeseed meal etc…) Please be aware that many seed meals do contain GMO’s. I would recommend an organic alfalfa meal.
1 part blood and bone meal
1 part lime
1 part bone meal or kelpmeal
***Out of fairness to the author, I won’t give out all the specifics, and the rates of application. I don’t agree with some of the author’s practices such as tilling and not using mulch, but it’s still a good book. So if you want all the specifics, buy the book.
Chemical fertilizers give the highest amount of NPK for the price, but that fertility is typically available very quickly and adds salts to the soil negatively affecting soil life. There are coatings now that fertilizer manufacturers add to slow the release down, but they still can’t fool the soil life. I would highly recommend avoiding these fertilizers, especially since there are so many other good options.
The Bottom Line
In the past my plan has been to make extensive use of chicken manure, living clover mulches, some straw and wood mulch, and compost to take care of my fertility. The only problem has been the cost and labor to apply said compost and mulch. Now that my clover living mulch is taking over, I am going to try the complete organic fertilizer. I would also like to start making a compost tea with a worm bin. I will still use chicken manure as well. In the future, I will continue to try other methods to further explore what works best for my site. I think the key to having good fertility is a diversity of materials and methods.
Reference: Steve Solomon, Gardening when it Counts