Monday, September 19, 2011

The Importance of Fertilizer

I've been growing vegetables since I was 12, and as a kid I remember we always had plenty of Miracle-Gro on hand to fertilize our plants with. I followed the directions on the package, and mixed some up every two weeks to feed the plants. Sometimes I'd do it even more, because more is better, right?

By the time I was a teenager I started getting into organics, and trying to work with Mother Nature instead of against her, since that never seems to work out. I started reading about how over-use of chemical fertilizers is bad, how it doesn't do much to help build up the soil, how it gives a burst of nutrition and then runs off quickly and pollutes waterways, and how over-fertilization can actually make your plants less healthy and less resistant to pests and disease.

I still believe all these things, but I think over the years I might have gone too far in the other extreme. When I was an undergrad I had a plot at a community garden, and I never put any fertilizer on my plants besides compost, which we had an ample supply of. I had bumper crops, so it seemed like fertilizer was completely unnecessary and a big waste of money. Plants do just fine with the nutrition Nature gives them, already present in the soil.

But now that I have my own private garden again, I'm starting to figure out that plants really do sometimes need a bit of a nutrition boost now and again. The trick is to know exactly what your plants really need, and in what form is best to give it to them.

Some of the garden failures I've had in the past couple of years have been due to easily identifiable causes. Not having any rain, for example, or squash vine borers killing all my squash. No amount of fertilizer would change that. But a few things have been a mystery to me, and those things might be explained by a nutritional deficiency.

One problem is how my pepper seedlings never seem to thrive. At first I thought it was because they were too cold. I start my nightshade seedlings in the garage around Yuletide, and it's cold in there, though not freezing. The tomatoes do fine, though they do look a bit purple, but the peppers are always pale, grow very slowly, and many end withering away and dying. They never look like the large, green, robust pepper seedlings from the nursery.

However, this year I started some peppers in the middle of summer, in the blazing heat, and they still looked weak and sickly after a while. I was always told that young seedlings don't need any fertilizer, because they're living off stored food from their seed. Except nightshade seedlings stay in their pots for a long time before they're planted out. Maybe they're in there long enough to use up their food reserves, and then need to be fed more. After all, they peppers do start out looking find, and don't start looking weak until about the second set of true leaves. They medium I use for starting seedlings is about a 50/50 mixture of the cheapest potting soil I can find and peat moss to lighten it up. I save the fancier potting soil with built-in fertilizers for plants that are going to be permanently living in containers.

So I went to the store and bought a bottle of fish emulsion, with an NPK of 10-1-1.

My pepper seedlings now smell like cat food, but look how happy they are only a week after feeding! It took a day or less for them to turn much darker green, and then they started growing more leaves right away.

I also put some fish emulsion on my brassicas, and it made them take off growing too. I do remember the warnings that too much fertilizer can make a seedling grow too fast, and they can get weak and spindly instead of stocky, but now I know what to do when I have seedlings that are looking a bit pale and yellowish and seem to not be growing much at all.

Now to move on to problems out in the garden. If you recall, this past spring I got a soil test done. I think it's extremely important to find out exactly what your garden needs, rather than having to guess. I was surprised and happy to find out my garden is doing great for just about everything except nitrogen. It was very low in nitrogen, which makes sense since nitrogen is the nutrient that gets depleted and washed out of soil the fastest.

My first potato crop here was very disappointing. I grew great potatoes at the community garden, but here I barely got back more than I planted. I could have just eaten the seed potatoes and saved myself some trouble. According to Texas A&M's soil testing website, potatoes need relatively high amounts of nitrogen. Much more than my soil has, that's for sure. Though my soil nitrogen is so low that A&M indicates only legumes would be truely happy in it. I probably got good potatoes out of my community garden because previous tenants of my plot had already built up the nitrogen levels in the soil.

But what would be the best way to get a lot more nitrogen into my soil? I want something that would be slow-release and long lasting, since nitrogen washes out of soil so easily, and I want something cheap since I don't have a lot of money.

Probably the best and most natural way is through legume cover crops, but even though we got some rain this weekend, I'm afraid that trying to grow a cover crop will end up costing me a whole lot of money just in water to keep it alive and growing. I use up too much water already just trying to keep my edible crops alive. Mixing some sort of nitrogen rich additive into the soil looks like it might be the best way to do it right now, at least until La Nina finally goes away and I can rely on rain to water any cover crops I might plant.

I've been doing some comparison shopping trying to find something that would be a cheap source of nitrogen. I'll probably end up trying several different things, but after looking at expensive bags of fertilizer at the stores, I finally decided to gives something a bit unorthodox a try.

I went to the grocery store and got the very cheapest brand of dog food they had. It was 44 lbs. on sale for about $16. I know it sounds a little crazy, maybe even wasteful, to pour "food" (even food for dogs) onto the ground and till it in, but the ingredients start out, "ground yellow corn, meat and bone meal, soybean meal, chicken byproduct meal, wheat middlings..."

If I had a dog, I'd probably give him or her food that's a bit better than that, but this ingredient list sounds like it has a lot of good plant fertilizers in it. After all, some popular organic fertilizers include corn gluten, blood meal, bone meal, and other waste products very similar to what they put in cheap dog food. And I'm pretty sure "fish emulsion" is mainly blended up fish guts. Plants love that kind of stuff.

I was a little surprised that Googling "NPK of dog food" didn't turn up anything, but I'm going to give this a try anyway and see what happens. I scattered some of the kibble over the bed I have cleared and ready for fall crops and raked it in a bit, then covered it with store-bought compost (since, like I said in a previous post, my compost pile is all dried out and won't decompose). I have a feeling I'll lose some of that dog food to scrounging wildlife, but I hope most of it is buried enough to get a chance to slowly decompose and add nitrogen to the soil over the winter.

This 44 lb. bag is going to last me a long time, but since I'm not sure exactly how much nitrogen is in there, I'll probably end up buying some of the more expensive stuff that's actually marketed as fertilizer for the crops that really need nitrogen badly, like potatoes. Since my soil test said I only need nitrogen, I could even go with "lawn fertilizer" that has a high N and hardly any P or K. But for my other crops that have been doing ok so far, even in my nitrogen deficient soil, I'll see how the dog food does for them.

This morning I went ahead and planted some of my biggest cauliflower seedlings in the bed that had the dog food mixed in. I saw one dung beetle rolling away a nugget of dog food a few times bigger than himself, but I was kind of impressed by that and let him have it. Haven't noticed any other wildlife digging around and stealing the food yet, so hopefully now with the rain it will start breaking down

I'm sure I still have a lot to learn about the best and cheapest way to keep up my soil fertility, but at least now I know a probable reason why some of my plants have failed to thrive.

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