Soil science is good to know when raising backyard livestock such as chickens, goats and sheep. The ability to integrate these livestock with backyard environments such as vegetable gardens, fruit trees and other types of land, such as pasture, is a truly fascinating opportunity and challenge.
Aside from providing food and companionship, backyard livestock also produce animal manure which, if used properly, can be a free resource with respect to soil regeneration, soil quality, and fruit and vegetable production. However, as we all intuitively know, mismanagement of livestock manure can contribute to food safety risks and nitrogen and phosphorus contamination of ground and surface water.
Here is some basic soil science and management information for how backyard livestock affects soil and some of the basic dos and don’ts of how best to manage backyard livestock on your property with respect to manure management.
Soil Science: A Little History
When you consider the fact that humans have farmed crops and animals on the same plots of land for approximately the past 5,000 to 10,000 years (depending on where they settled after the last ice age), we have learned a decent amount on how best to utilize animal dung for increased food production. Animal manure is a truly amazing resource that has helped humans increase crop production and crop variety wherever they have settled. However, mismanagement has led to disease, overproduction and water contamination.
Knowing a little about the chemistry and microbiology of animal manure and soil and how they interface with each other is important at a historic, global and, of course, an individual level. Believe it or not, not all livestock poop is created equally. While many similarities exist with respect to chicken, goat and sheep (and other livestock) manure, some important differences occur, too. Big picture, none of them can be directly applied to crops as animal feces is full of harmful bacteria such as virulent forms of various bacteria such as E. coli, salmonella and campylobacter. These bacteria can thrive in livestock guts, be shed in feces and contaminate our backyard fruits and vegetables.
In some cases, they can get inside plant cells as opposed to just being on the surface of your fruits and vegetables. This scenario makes washing ineffective at preventing ingestion and human infection. This is especially true on what are referred to as “touch crops” such as spinach and other leafy greens which literally touch the ground. Raw animal manure can easily contaminate these types of crops which are often eaten raw creating a significant food-safety risk.
Chicken, sheep, and goat manure share commonalities as valuable organic fertilizers, yet their compositions and characteristics exhibit notable differences which include:
- Sheep and goat manure tend to have higher nitrogen content compared to chicken manure. In contrast, chicken manure has relatively higher phosphorus.
- The carbon-to-nitrogen ratios differ among these manures, affecting microbial activity during decomposition. Chicken manure, with a lower carbon-to-nitrogen ratio, decomposes faster, while sheep and goat manures, with higher ratios, contribute to longer-lasting soil improvements.
- The texture and consistency of the manures vary. For example, chicken manure tends to be higher in moisture content, while sheep and goat manures are drier. From a practical perspective, this influences the rate of decomposition and the potential for nutrient leaching.
Understanding these similarities and differences and your soil’s chemistry with respect to potential imbalances in nitrogen, potassium, phosphorous and other elements can allow gardeners to tailor their manure applications to specific crop needs, optimizing the benefits while mitigating potential challenges associated with nutrient imbalances or overuse. In a perfect world, it’s ideal to have your soil tested to see what it is lacking in before applying raw material. Ultimately, the judicious utilization of chicken, sheep and goat manures contributes to sustainable soil management practices.
Note: If you apply raw manure to even inedible plants, you run the risk of applying too much phosphorus or nitrogen which can damage or even kill the plant. While applying raw manure is not recommended for backyard farmers, if for some reason you must apply raw manure, in a backyard setting you should not harvest anything for human consumption for at least 120 days after the application of the raw material. This 120-day rule isn’t an exact science, but it does give an easy-to-remember time. In addition, if excessive levels of raw manure are applied, leaching and contamination of surface or ground water can occur. In addition, never apply raw manure when it’s raining or to steep fields as this process is further exacerbated.
Composting
For a backyard gardener, the best approach to dealing with livestock manure is to compost the material and then apply it as a soil amendment. As the feces decompose naturally via the help of various microbes, a chemical transformation occurs which causes the release of organic matter which has several beneficial effects on the soil. This, in turn, creates an environment conducive to microbial activity, promoting the proliferation of beneficial bacteria and fungi. When you apply this material to your soil, the soil is transformed in the following ways
Increased Soil Organic Matter
This, in turn, creates an environment conducive to microbial activity, promoting the proliferation of beneficial bacteria and fungi.
Improved Soil Structure
This enhances water retention capacity. In addition, compost improves soil’s ability to hold nutrients and delivers much-needed nutrients. It improves nutrient retention by increasing the soil’s cation exchange capacity and delivers needed food for the plants in the form of nitrogen, phosphorus and potassium. As you can imagine, it’s only useful if the composted material can be integrated into the soil and not just applied to a hard dirt pad. To that point, it should also be noted how livestock manure can be misused and be damaging to soil chemistry and quality. The big picture is that applying livestock manure to cropland increases the amount of organic matter in the soil which improves the soil structure and can increase the soil’s ability to hold water.
The soil science behind composting, if done properly, inactivates most pathogens such as bacteria and even weed seeds that may be present in the material. The operative word is most. Harmful bacteria can persist in smaller amounts, so washing your hands in addition to washing any plants that you eventually consume is critical. This is especially true for “touch plants” described previously.
Compost Ingredients
All you really need is livestock poop, plant material (aka carbon), oxygen and water. Note: You can use discarded fruits, vegetables and even grass clippings and wood chips. However, the proportions of the ingredients are important. Too much or too little of these ingredients may produce bad smells or inhibit the beneficial bacteria from growing and transforming the material to compost.
The ratio of ingredients is key. You typically want a carbon-to-nitrogen ratio of approximately 30:1 on a weight basis. In other words, for every 2 pounds of plant material, you would want about 1 ounce of livestock poop. This ratio plus some water will allow the “correct” bacteria to grow which are essential for transforming the uncomposted material to composted material.
As the good bacteria grow and displace the bad bacteria, heat is generated. The heat is key to helping the good bacteria grow and inactivating harmful viruses and bacteria. Getting to a temperature between roughly 141 to 155°F is very important because this is the temperature where pathogenic bacteria die and weed seeds are inactivated.
Reaching that temperature can be challenging in certain colder and wetter climates and can also be challenging if you compost pile is too small, which is a common issue for backyard chicken keepers. With respect to the weather, if you live in a cold and wet environment, consider composting when the temperature is warmer. In addition, while water is one of the key ingredients, you don’t want too much. You basically just want the material to be somewhat moist.
Make sure you have a dedicated raised secure container for composting (or an alternative method called “sheet” or “lasagna composting,” where you place the mixed material on cardboard or wet newspaper and then put a layer of carbon on top). Rodents, insects and birds will likely try to get into your black gold and eat some of the ingredients listed previously. Unfortunately, they often poop where they eat which can be a serious food safety issue if you take your compost and then spread it in your garden.
One advantage of the raised system is that the pile can be turned easily (especially if there is a crank to turn the compost container). The goal here is to introduce oxygen which helps the good bacteria grow.
Completed Compost
When the compost is done and ready to use is objective and subjective.
Objective: The internal temperature of your compost pile should reach a temperature of between 141 to 155°F. You can get a special thermometer for compost which is basically a metal probe with a thermometer at one end. This way you just need to poke the pile and measure the internal temperature as opposed to breaking open the pile and measuring the temperature.
Subjective: Compost should feel and smell like rich soil and not like poop. The transformation should be obvious, but there is no specific objective feel and smell. Like everything this comes from experience. However, when in doubt, compare it to store-bought compost.
Composting can be a little tricky for backyard livestock keepers. However, it can also be a very satisfying activity in that you are fully integrating your chickens and plants in a way that humans have done for thousands of years. Like everything, composting can be perfected with practice, and even if you live in a cold and wet environment, it can be done. Ultimately, you just need to figure out what soil science works best for your system. With a little experimentation, you can come up with an approach that works best for your specific situation.
This article about soil science was written for Chickens magazine online. Click here to subscribe.
