Thursday, February 16, 2012

Confused about Fertilizer?


Even if you have perfect soil, your garden needs regular applications of nitrogen to replace the nitrogen removed by crops as you harvest them and from erosion by wind and rain.  Contact your local county extension agent or garden center to obtain instructions for completing a soil test to determine all the nutrients your soil needs. 

The easiest solution is to add chemical fertilizer like 10-10-10.  It provides the three main nutrients, nitrogen, phosphorus, and potassium, in equal amounts.  Many garden advisors suggest adding it to fulfill the needs of all garden plants.  However, it is not the best option. 

Chemical fertilizer kills soil microbes and garden critters like earthworms.  If you put 10-10-10 on everything, you will add excess amounts of some nutrients, and perhaps not enough of others.  Rain washes excess fertilizer into streams and disrupts ecosystems. 

Organic fertilizers are a better choice.  They can seem expensive when compared to chemical fertilizers, but in the end, they are cheaper.  Blood meal provides nitrogen, potash gives the soil phosphorus, and bone meal supplies potassium.  At a local store, three-pound bags of blood meal, potash, and bone meal cost about $6.50 each.  A 20-pound bag of Black Hen fertilizer, which is composted chicken manure, is about $7.  Bone meal, for example, has an N-P-K ratio of 6-9-0, which means it has 6 parts nitrogen, 9 parts phosphorus, and no parts potassium.  Black Hen fertilizer has a N-P-K ratio of 2-3-2.  Bone meal is about three times as strong as Black Hen, but the bone meal costs about six times more than the Black Hen. 

An even cheaper choice is alfalfa meal or cottonseed meal, available in 50-pound bags at feed stores for about $15.  Alfalfa meal has a N-P-K ratio of 2-1-2, and cottonseed meal, available in approximately the same amount and quantity as alfalfa meal, has a N-P-K ratio of 6-4-1.5.  Farmers use alfalfa meal and cottonseed meal as animal feed, but they work well as fertilizer.  I prefer to use alfalfa meal instead of cottonseed meal because farmers apply more pesticides to cotton than they do to alfalfa, and farmers grow GMO cotton but I do not think there is a GMO version of alfalfa.

Not everyone has room for 50 pound bags of fertilizer or can store bags of Black Hen fertilizer somewhere the smell will not offend anyone.  In those cases, the more expensive small bags of organic fertilizers are the best option.  For a small garden, they will last the season and maybe longer.  Organic fertilizer stays in the soil longer than chemical fertilizer, and this benefit offsets the higher initial cost of organic fertilizer as compared to chemical fertilizer.  They also actually improve the soil’s health instead of destroying soil life.  For me, one of the best benefits is that although composted chicken manure or bone meal are a little icky, you do not have to worry about the fertilizers burning the hands of children who want to help in the garden.  

Below are two other internet references that give a discusion of chemical versus organic fertilizer.  Here is a link to the benefits of organic fertilizer over chemical fertilizer, and
this is a YouTube video from Atlanta Gardener about the living soil organic fertilizer creates. 

2 comments:

  1. Post explain some good data about the fertilizers. I found this post insightful and also clear my doubts about the usage of the fertilizers. I will look forward to this share..

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