Drawing by Beatrix Potter from “Peter Rabbit.” Perhaps if Mr. McGregor had known how great rabbit manure was for his garden, he would have made friends with Peter and perhaps orchestrated a mutually beneficial arrangement. Rabbit manure is packed with nitrogen, phosphorus, potassium, and many minerals, lots of micro-nutrients, plus many other beneficial trace elements such as calcium, magnesium, boron, zinc, manganese, sulfur, copper, and cobalt just to name a few. And it won’t burn your plants.
Chemical Fertilizers Alone Eventually Fail
Fertilizers fall into two general categories: organic, or natural, and inorganic, or chemical. Most plants benefit from fertilizing. Natural fertilizers are those formed through decomposition of organic matter, while chemical fertilizers are manmade. Natural fertilizers improve the texture of the soil and increase the amount of beneficial microorganisms. Inorganic chemical fertilizers feed the roots of the plants and do little to improve the soil.
Your plants are not going to know the difference between organic or inorganic nitrogen but the microorganisms in your soil will. Your plants will grow with the continued use of chemical fertilizers. However, continued use of inorganic fertilizers increases the gardener’s dependence on purchasing them again year after year because each year, the quality and texture of the soil will become worse as chemical fertilizers do not feed the microorganisms in the soil and they die off.
Chemical Fertilizers Only Nourish the Chemical Content of soil.
All soils consist of a chemical, physical and biological content. The chemical part refers to the nutrient content (nitrogen, phosphorus and potassium). This is the only part of the soil that is fed by chemical fertilizers. The physical part refers to the structure and texture of the soil (sand, silt, clay and organic material). The biological component includes the fungi, bacteria, protozoa, arthropods and other micro-organisms.
Organic Fertilizers nourish all components of the soil as they feed and encourage micro-biological activity.
The Micro-organisms are the biological content of soil. Mycorrhizal fungi attach themselves to plant roots and increase the absorptive ability of roots by 10 to 1,000 times, resulting in an increased drought tolerance. Mycorrhizae also release antibiotics into the soil that immobilize and kill disease organisms. They also are capable of releasing powerful chemicals into the soil that dissolve hard-to-capture nutrients, like phosphorus and iron.
They can also help improve soil structure by supplying organic “glues” that bind soil particles into aggregates, thus, improving porosity. Soils with poor porosity tend to become waterlogged and disease-prone. As you can imagine, these little guys do a tremendous job of keeping our plants healthy and thriving.
All soils contain both bacteria and fungi, and both can be either beneficial or pathogenic. It is our job as gardeners to encourage the good guys. We do this through gardening practices like annual applications of compost, crop rotation, minimal applications of pesticides, no-till gardening techniques and good water management.
Commercial Organic Fertilizers – Biofertilizers
Biofertilizers contain different types of fungi, root bacteria or other microorganisms. They form a mutually beneficial or symbiotic relationship with host plants as they grow in the soil. Biofertilizers are a cheap, easy-to-use alternative to manufactured petrochemical products. Biofertilizers restore normal fertility to the soil and make it biologically alive. They boost the amount of organic matter and improve soil texture and structure. The enhanced soil holds water better than before. Biofertilizers add valuable nutrients to the soil, especially nitrogen, proteins and vitamins. They take nitrogen from the atmosphere and phosphates from the soil and turn them into forms that plants can use. Some species also produce natural pesticides.
Biofertilizers increase yield by up to 30 percent because of the nitrogen and phosphorus they add to the soil. The improvement in soil texture and quality helps plants grow better during periods of drought. Biofertilizers help plants develop stronger root systems and grow better. Biofertilizers also reduce the effects of harmful organisms in the soil, such as fungi and nematodes. Plants resist stress better and live longer.
The soil must contain adequate nutrients for biofertilizer organisms to thrive and work. Biofertilizers complement other fertilizers, but they cannot totally replace them. Biofertilizers lose their effectiveness if the soil is too hot or dry. Excessively acidic or alkaline soils also hamper successful growth of the beneficial microorganisms.
NOTE: I’ve never used a biofertilizer before but I just ordered a gallon bag for the Garland Community Garden. This comes with no recommendation on my part: Wakefield Biochar Soil Conditioner one gallon bag from Amazon for $17.99. I’ll apply to Charlie’s tomatoes at the garden and then to one of the tomato plots he has at his house. I’ll let you know how they grow.
Non-commercial Organic Fertilizers
Use about two-thirds brown matter –pruned branches from shrubs, dry leaves, animal droppings and so on – and one-third green-matter, such as food scraps, green leaf litter and grass. Water your compost well and make sure it is aerated. Soon bacteria and microorganisms will colonize your compost pile and turn it into useable material for adding to your soil.
Organic mulches such as straw, grass clippings, newspaper and woolen clothing break down more slowly than other forms of organic matter, but they offer other benefits that make them incredibly useful. As they slowly break down, releasing nutrients back into the soil, they provide insulation from extremes of temperature, cooling the soil in the summer and keeping it warm in the winter. They also help retain moisture in the. And, they act as a weed barrier or to cover existing weeds and break them down into organic matter.
Legumes are the family of plants that have the best nitrogen-fixing ability. Certain bacteria that live in their roots convert nitrogen into a soluble form of the element that plant roots can take up and use to grow. At the garden we grow Austrian Winter peas as our cover crop.
Cover crops serve a lot of functions. They help to minimize water evaporation from the soil, they provide shade and, importantly, they add organic matter. This is because cover crops, such as potatoes and pumpkin, have deep roots that open up the soil, allowing water and nutrients to penetrate into it and stimulating microorganism activity. These roots also help maintain the integrity of the soil, and the leaves of cover crops rot in place and return their nutrients to the topsoil.
Green manure crops are similar to cover crops, but rather than remaining in the soil and naturally decaying in winter and revitalizing in spring, they are deliberately cut and then left on the surface or forked into the soil to add organic matter.
My own personal preference for animal manure is that it is fully composted and broken down from several months in the compost pile prior to use in the garden. At the Garland Community Garden we currently use only horse manure. Certain manures such as horse, rabbit and alpaca can be applied directly to the garden soil without danger of burning the plants. This is not true of other manures such as that from a cow, pig or chicken.