Humus contains organic material - living tissue that has died and its components are being recycled. Microbes like bacteria and fungi work on organic material, breaking it down into its smaller building blocks that can then be taken back up by a new plant. Humus has a structure that makes it easy for living plants to find and take up the nutrients. Some of the salts, for example, stick on the ends of long wavy molecules that are easy for plants to grab. Humus is dynamic and always changing. The community of microbes can be very diverse and stable as long as more and more organic matter is fed to the soil to maintain all those microscopic creatures (Donahue et al. , 1983).
Plants also need lots of water for proper growth. Water will just run through sand or ground rock so humus along with the clay holds water in the soil.where it will be available to plant roots. Soil provides the matrix where seeds are first nurtured. When the seed first starts to grow, it pushes out tiny roots to begin interacting with the soil to find water and nutrients. A green, leafy stem pushes up out of the soil reaching for the sky because plants receive energy from the sun to make them grow. The water at the top of that stem evaporates into the air and pulls more water and nutrients up from the soil into the plant. ...
Unfortunately, when they eat from the plants on a farm, they are eating our food, so any farming system must consider these pests. Conventional and organic farmers take different approaches to these two main issues: maintaining enough nutrients to feed the plants and protecting plants from pests.
Conventional agriculture emphasizes maximizing yield and farming efficiency. These farmers look at the growing population and say that we need all the food we can possibly grow. Such farms use chemical fertilizers to replace the nutrients that plants take up out of the soil. These are generally, mineral salts of nitrates, phosphates, and potassium. These are applied to the field as dried pellets that dissolve in water. By putting these nutrients into the soil, the conventional farmer is certain that his plants will have enough for the fastest and maximum growth. Such plants often take up lots of water with the nutrients which swells them and makes them look fat and juicy and easier to sell Of course, every time it rains or the farmers irrigates the field, some nutrients will travel with the water wherever it go - sometimes into nearby rivers and streams, so often nutrients are lost when applying fertilizers. Such outside nutrients can sometimes disrupt the delicate ecosystem balances in the waters where they end up.
Conventional farmers also act strongly when pests like insects or weeds interfere with growth of their crops. These farmers spray specially made poisons on or around plants to kill off the pests. Many farmers also spray 'prophylactically' before pests arrive so plants will not have any losses or even markings from insect pests. Unfortunately, these poisons are not specific to one certain kind of insect.