We have all heard that adding compost to your soils can help in water retention. But how big is it? Research out of Kansas State University says that increasing the organic matter in your soil by just 1% can increase the water holding capacity by 25,000 gallons over 1 acre. For a homeowner that equates to an additional 578 gallons of water for each 1,000 square feet!
With last year’s drought in many parts of the U.S. this is big news. The biggest issue with drought is when the soils dry out they can no longer supply water to your plants — called “wilt point” — and it is really hard to get them re-hydrated down deep. Surface irrigation is great for the upper 2-3″ but if your lower soils are super dry they will suck water and not give it back to your plants. It’s kind of like a really dry sponge… At first the sponge doesn’t want to accept any water because it is crispy dry and once it starts to take in a little it is hard to squeeze any back out.
Compost added to your soils does a number of super positive things… 1) It holds a lot of water, 2) It helps to hold open the soil profile for better air movement, and 3) It adds essential biology.
There is 1 easy way to get compost in your soil and 1 rather hard way. The hard way is to pull out your existing lawn, import 6 to 9 cubic yards of compost for every 1000 square feet, rototill it in deeply, grade, rake and roll and then either seed or sod the new lawn. Not very easy.
The easy way is to core aerate your lawn (we recommend double or even triple coring passes) and then apply a thin layer of between 1/4″ to 1/2″ over the surface. Rake it in and you are done. This will require only 1 to 1-1/2 cubic yards of compost per 1000 square feet.
When adding compost to your yard using the second, easy method, you will need to repeat the process yearly until you have reached the desired amount of organic matter in your soils. Lawn soils should be no less than 5% and no greater than 12% organic matter. If you chose the first method of tearing out your lawn, fixing the soils and then replacing the lawn, you will not need to repeat adding compost yearly. In addition, you will get immediate results of having compost rototilled down deeply into your soils.
And while we are on the topic of organic matter in your soil… Do not remove your lawn clippings when you mow your yard. When you do, you are working against the very thing you are trying to establish and that is adding more organic matter. One of the basic principles of organic landscaping is that your plant’s best food is its own foliage. Everything the plant needs it generates on its own. When you remove it you now need to figure out how to bring back in the very thing you just removed. So let it lie, make your lawn happy and reduce your yard work!