Tag Archives: soil

Garden Advice

Common Nutrient Deficiencies in Plants

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Spotting nutrient deficiencies in your plants can be challenging, especially if you’re new to gardening. Here are what a few common deficiencies look like and how to correct them.

Soil Nutrients

Nutrients in the soil can be divided into two categories macronutrients and micronutrients/trace minerals.

The first category, macronutrients, comprises primary nutrients nitrogen, phosphorus, and potassium and secondary nutrients sulfur, magnesium, and calcium. If you think your plant has a nutrient deficiency, these are the likely culprits.

The second category, known as micronutrients or trace minerals, includes boron, chlorine, copper, iron, manganese, molybdenum, and zinc. While these are still important to plant health, they’re needed in such small quantities that it’s less likely your plant is deficient in one of these micronutrients.

You can read more detailed descriptions of what all of these nutrients do in our post, Understanding Soil Tests.

Nitrogen Deficiency

A nitrogen-deficient plant will grow slowly and lack vigor. The leaves may turn pale and yellow before dropping off, with the oldest leaves dropping first.

Note that it’s easy to overdo it when adding nitrogen, especially if you’re using chemical fertilizer. Adding too much nitrogen will cause lush, dark green foliar growth at the expense of fruit and flower production.

There are many ways to add nitrogen to your soil. While you shouldn’t directly apply it to plants, animal manure is a good choice if you have access to it. Compost will also add some nitrogen, or you can add seaweed or kelp meal, fish emulsion, bone meal, coffee grounds, soybean meal, or cottonseed meal. Using legume cover crops also helps to increase your soil’s nitrogen levels.

Phosphorus Deficiency

A plant that is deficient in phosphorus will also lack vigor and may be stunted. It might drop fruit before it’s ripe or not produce fruit at all. The lower leaves may appear red or purple.

You can add phosphorus to your soil using rock phosphate, greensand, compost, or bonemeal.

Potassium Deficiency

Potassium deficiency will probably be most apparent in your plant’s leaves, which may be mottled or curled or have brown edges. The plants will also be weak and have stunted root growth. They will likely be more susceptible to disease and pest issues.

Good potassium sources include manure, compost, seaweed or kelp meal, potash, granite dust, greensand, and wood ashes.

Sulfur Deficiency

While sulfur is a macronutrient, a sulfur deficiency is much less common. Signs include stunted growth and pale, yellow leaves.

Add sulfur with gypsum, compost, or sulfur.

Magnesium Deficiency

If your plant is deficient in magnesium, you may notice poor flower and fruit production, stunted growth, and dropping leaves. Leaves may also appear mottled with yellow/white patches or purple/brown patches between the leaf veins.

To correct a magnesium deficiency, add limestone, manure, compost, or greensand.

Calcium Deficiency

Calcium deficient plants may die back or have buds that die. Their leaves will likely appear burnt, curling, or have necrotic leaf margins. You may also notice issues like blossom end rot and other signs of tissue necrosis.

Use oyster shells, eggshells, limestone, gypsum, or fishmeal to add calcium to your soil.

Notice how similar a lot of these symptoms are?

If you’re having problems with nutrient deficiencies, the best advice is always to get your soil tested. It isn’t complicated or expensive and will tell you precisely what you need.

It will also tell you what your soil’s pH is. Soil pH can affect plants’ nutrient uptake and may cause deficiencies even if your soil is otherwise fine.

If your soil test comes out fine, your plants may be struggling due to over or underwatering or disease issues.

How do I prevent deficiencies?

The first step you should take is to develop a garden rotation plan that includes cover crops. They’re excellent for preventing erosion and adding nutrients to your soil.

Yearly applications of good quality compost can provide a wide range of nutrients to your soil.

Garden Advice

What’s a Nitrogen Fixer?

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Nitrogen fixing plants have a symbiotic relationship with specific bacteria. The bacteria colonize the plant’s roots and pull nitrogen out of the atmosphere. The bacteria uses the nitrogen and then it becomes available to the plant.

Nitrogen fixing plants include most plants in the legume family. They also include certain grasses like buckwheat but legumes are generally the most efficient. 

Why are they important?

Nitrogen is key for plant growth. Plants require it in order to perform photosynthesis. Yellow or pale leaves can be a sign that your soil lacks sufficient nitrogen. Rotating nitrogen-fixing crops through your garden replenishes nutrients in the soil without resorting to using synthetic fertilizers. 

Many nitrogen fixing crops, like those listed below, are used as cover crops or green manures. Like other cover crops they help prevent moisture loss, reduce erosion, and provide habitat for beneficial insects and fungi all while adding nitrogen to the soil. Using cover crops is in investment in soil health.

Nitrogen Fixing Cover Crops

Other legume crops like beans and peas are also nitrogen fixing. Pole beans are grown in the “Three Sisters” garden technique because they help provide nitrogen for the heavy-feeding corn.

Growing Cover Crops

Nitrogen fixing cover crops can be used in different ways. Biennial or perennial crops like clover are often grown for a season or year and then tillled under. This process adds organic matter to the soil and makes the plants’ nitrogen and other nutrients available to your crops. Alternatively winter-kill or annual crops like Sunn Hemp die back on their own and can be used as mulch. As they decompose they add nutrients and organic matter to the soil. 

These nitrogen fixing crops are also perfect for permanent pathways between rows or beds. Clover pathways in particular can be mowed through the summer. The clippings make excellent mulch for the adjacent beds.  

You can find more individual information under individual variety descriptions. 

 

Garden Advice

Understanding Soil Tests

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If you’ve never had your soil tested you may want to consider it. While soil tests may seem like something more suited to commercial growers than backyard gardeners they’re actually quite simple and affordable. In fact some local extension agencies and/or state colleges offer this service for free. While you can purchase at home soil tests generally having it professionally done is a good place to start. 

Here’s what you can expect from a soil a test and what it will mean for your garden. 

Macronutrients

Primary Nutrients

The following three nutrients are considered the primary nutrients and the probably the most discussed by gardeners.

  • Nitrogen 
  • Phosphorus 
  • Potassium 

Nitrogen is important for plant’s vegetative growth. Phosphorus helps in root and flower development. Potassium promotes vigor. These are found in a variety of commercial fertilizers and homemade garden amendments.

Secondary Nutrients

  • Sulfur 
  • Magnesium
  • Calcium

Calcium helps plants build strong cell walls, magnesium is an important part of chlorophyll, and sulfur is important for the growth of roots and seeds. Just like primary nutrients these secondary nutrients can be purchased in commercial amendments or you can make homemade ones.

Micronutrients/Trace Minerals

Some soil tests will give you the option of testing for micronutrients or trace minerals. These are minerals that plants need in very small amounts. 

  • Boron 
  • Chlorine
  • Copper
  • Iron
  • Manganese
  • Molybdenum
  • Zinc

Unless you suspect a problem testing for these is probably unnecessary. Most soils have enough to keep plants healthy and deficiencies in these minerals aren’t caused by their lack of presence in the soil rather an inability for plants to take up the nutrient because of other problems such as drought stress or incorrect pH. 

These minerals are also typically present in large enough quantities for gardens in any organic fertilizer or other amendments even simple, good quality compost. 

Soil pH Level

Another important part of your soil test is your soil’s pH. pH is the measure of how acidic or alkaline your soil is. It’s an important feature on your soil test as it affects soil nutrient availability and microbe activity. This means that even if a nutrient is in your soil it may still be unavailable to plants do to your soil’s pH.

It’s also worth noting that some crops like blueberries and potatoes prefer more acidic soil than others. 

Amending Your Soil

Once you get your results you can amend your soil as needed. There are a variety of products available commercially or you can use homemade garden amendments like compost and compost tea, manure, coffee grounds, egg shells, pine needles and more. 

You may be able to get personalized recommendations from your local extension agency or soil testing service.

When adding any garden amendment it’s important to thoroughly research its effects on your garden. Certain amendments like oyster shells for calcium can affect your soil’s pH and may affect the availability of other important nutrients. You also want to avoid adding too much of anything to your garden as this can be just as bad as too little. Excess nutrients can also run off into streams and other water bodies causing toxic algae blooms.

11 Free Organic Methods to Add Nutrients to Your Garden

Seedlings

If you start your own transplants at home don’t forget about the nutrients they need. Buying or mixing a good quality potting mix is important to their success. One of my favorite ways to give seedlings a quick boost is to add a bit of compost tea or liquid kelp to their water. I typically use about 5 TBS per gallon of water. 

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