The primary nutrients used by plants are nitrogen (a functional part of chlorophyll and essential in the formation of amino acids and proteins), phosphorus (essential in energy transfer, photosynthesis, respiration and cell division) and potassium (required for the synthesis of both carbohydrates and proteins). Calcium, sulfur, magnesium, boron and other essential nutrients assist in the vegetative and reproductive phases of plant growth and ultimately harvest.
 
For plants, the predominant source of these elements is soil, the degree to which is largely dependent on the parent material of the soil (what lies beneath — bedrock, etc.) and influenced by climate, environment and human interventions. Farming practices too can have a significant impact on the quality of agricultural soils.
 
Tillage
Conventional tillage (plowing with a moldboard plow that turns over deeper layers of soil) is the most severe form of tillage. Although this technique helps control weeds, it also exposes the soil to wind, rain and erosion. “Conservation tillage” and “no-till” farming leave at least 30 percent of the previous crop’s residue on the soil surface, where the next crop is planted.
 
Crop Rotation
Another soil-building practice is alternating the kinds of crops planted in a field. Crops are rotated by botanical family to alleviate pest and disease pressure and replace nutrients taken up by the previous crop. Vegetable crops within the same botanical family follow a four-year crop rotation so as not to perpetuate diseases and pests to which those plants are susceptible.
 
Cover Crops
Planted between growing seasons, cover crops serve several purposes. They act as nutrient sponges that take up and bind in place nitrogen and other nutrients left over from the previous crop. They also build organic matter, assist in weed management, improve drainage, keep nutrients from moving to waterways and decrease sediment loss and erosion.
 
The Nutrient/Nutrition Connections
Plants that remove significant amounts of nutrients (called nutrient uptake) at harvest tend to have good levels of that nutrient (called nutrient removal) as a food. For example, potassium is deposited in the tuber of the potato plant during the reproductive phase of tuber growth — making potatoes a good source of dietary potassium.
 
However, the correlation between soil nutrients and those present in the plant is not exclusive. Insufficient potassium in the soil may result in smaller potatoes with lower starch content, but not necessarily lower potassium. And plants grown in soil with sufficient nutrients still can have nutrient deficiencies in the foods they produce; incorrect soil pH, drought or root system damage can limit a plant’s ability to take up nutrients.
 
Some research suggests that nutrients in fruits and vegetables have declined over time due to genetic dilution of breeding cultivars for higher yields. Other research has shown significant variances in mineral and flavonoid composition of fruit and vegetables across growing seasons, indicating that cultivar selection, growing conditions and crop production practices such as fruit thinning (removing a portion of fruit from a plant so the remaining fruit ripens more evenly) may be strong contributors.
 
According to the Food and Agriculture Organization of the United Nations, the most cropland acreage using conservation agriculture practices is in the U.S., Argentina and Brazil, respectively. Data from the U.S. Agricultural Resource Management Survey show that in 2009, nearly 36 percent of U.S. cropland planted to eight major crops (barley, corn, cotton, oats, rice, sorghum, soybeans and wheat) had no-till operations.
 
Leading the trend are farming families — particularly farms throughout the Northern Great Plains, Heartland, Mississippi Portal and Eastern Uplands regions — who are striving to produce healthy foods and maintain healthy soils for future generations.
 

Related Videos from the USDA Natural Resources Conservation Service

"Soil Stories"

"Under Cover Farmers"

Jennie Schmidt, MS, RD, is a member of a third generation family farm practicing Continuous Quality Improvement on their soils.

My family predominantly lives on food we grow ourselves or which is grown locally by our neighbors. Our kids raise 4-H hogs and one always goes to the freezer each year once the county fair is over. Our other main source of protein is venison, hunted on our own property. I was taught canning and freezing by my mom, and so I continue the tradition of “putting up” food when it is in season for use in our menus in the offseason. I buy local peaches, strawberries, blueberries and other produce to can or freeze and use to make yummy dishes all year long. In this sense, I am very much a “locavore.”

The “buy local” movement has a lot of momentum and has done great things for local farm economies, not to mention the health benefits of eating food produced in season and from within your own community. But having lived abroad and traveled extensively and thought of all the farmers I know around this globe, I’ve decided there are merits to being both a “locavore” and a “globavore.”

I love being a globavore mainly because I know so many farmers in so many countries around this world. My family has hosted International 4-H Youth Exchangees (IFYE’s) and young farmers for nearly 30 years. These young farmers and IFYE’s came from over 20 different countries making our connection very meaningful and personal. In turn, members of our family have been able to travel to visit and spend time with several of these farm families on their farms in foreign lands. “Know Your Farmer”—the USDA’s program to encourage local food communities—takes a whole new definition when you’ve lived and worked with farm families around this globe.

I grew up on the edge of the Berkshire Mountains. I love New England maple syrup, made by my dear friends who still tap trees and boil sap the old fashioned way. I think of them every time I use their syrup on my pancakes or French toast.

Cabot Cheese is one of my favorite brands because I know dairy farmers in the New England area whose milk is processed into their yummy cheeses.

Our neighbors milk cows for Land O’ Lakes and the Maryland-Virginia Milk Producers Cooperative. Supporting those brands helps our neighbors.

I love Vlasic pickles. I think of my cucumber-growing, fellow Eastern Shore woman-farmer Hannah every time I eat pickles.

I buy Perdue, Mountaire, or Allen-Harim chicken.  I can’t count on my fingers and toes the number of friends I have who are poultry farmers. My friend Jen is our county extension agent and, along with her two boys, runs a chicken farm. I know how much they care for their chickens and know I am getting a quality product supporting a fellow farmer when I buy those brands.

When our freezer runs low on our own meat, I look for Leidy’s or Alderfer brand pork out of Pennsylvania. My friend Jen is a hog farmer. I’ve been to her farm. I know how she operates and look for the brand that buys her hogs.

It is not a mistake that I selected three female farmers to feature in this blog, either. I am proud to be a woman farmer along with these other strong, intelligent women. We’re not alone either. Did you know that 30 percent of U.S. farmers who grow your food are female?

When my branch of Schmidts left Germany for America, another branch of Schmidts set out for Chile. These distant cousins are now one of the largest table grape growers in that country. I think of them every time I buy Thompson seedless from Chile at my local supermarket. A relative of mine grew those grapes.

We have dear friends who farm paprika peppers in South Africa. I think of them and remember my time in South Africa every time I use paprika as a seasoning.

I was fortunate to travel to Vietnam in January 2011. I think of the rice and tilapia farmers I met when I consume either of those food items and hope they are doing well. While I don’t “know” them well, a face-to-face meeting with a farmer makes you have a better connection to how your food is produced, regardless of location.

That trip highlighted how food is globally interconnected and how important U.S. agriculture is to so many people outside our borders. Visiting Hong Kong, Vietnam and Taiwan, I understood the importance of U.S. farm exports to feed people in countries with too little land mass to feed their own population. U.S. farmers support so many people beyond our own farm-gates, supporting globavores by choice and necessity.

On the flip side, the majority of what we grow on our family farm stays within 100 miles of our property. This distance is the well-used rule of thumb for defining local by many who have hitched their wagon to the local food movement. From our farm in Maryland, 100 miles reaches to Pennsylvania, New Jersey, Virginia, West Virginia, Delaware and Washington, D.C. Whether its tomatoes to a cannery, fresh market green beans to a distributor, grapes to a winery, corn to a grain elevator, or soybeans to a tofu-maker, much of what we grow stays local. Our family farm supports many other local businesses, both as a buyer of items we need to operate our farm and as a seller of raw food or feed items to other family-owned local business.

The fabric of the rural economy is very much a locavore economy, not only of food, but of products and services to and from family farms.

Locavore or Globavore, food is about relationships.  “Local” to me can be grown thousands of miles from me, but grown by a friend or distant relative. Knowing your farmer isn’t about distance, it’s about relationships. Consumers can connect their relationship to food by patronizing farmers markets, CSAs, farm stands, creameries or wineries, and by looking for local products in the grocery. But don’t lose sight of the fact that my friend Hannah may have grown those pickles you’re crunching, my friend Jen may have raised that bacon you had for breakfast, or that my tomatoes may be in the spaghetti sauce you had for dinner last night. Just because our faces are not on the product, or you didn’t buy it direct from one of us, doesn’t mean that item wasn’t grown by a family farmer who main interest in producing a safe and healthy food for your consumption.

Harvest is both busy and reflective. It can be rewarding or disappointing, depending on how well Mother Nature treated us this year and if we have had any major and expensive equipment breakdowns or other interferences in our ability to get the crops in. So far, with the exception of a second year of drought in our region –though less harsh than last year’s – this year harvest has gone reasonably well and crops are doing better than anticipated.

Allow me to share part of my story. I started life as a Registered Dietitian 20 years ago. I worked in both clinical long-term care, and public health arenas before “leaving” the profession to work full-time on our family farm. Frankly, I feel like I never left the profession because farming is the front-line of nutrition. I say I literally practice nutrition “in the field.”

Our family farm is a third-generation, 2,000-acre, highly diversified operation producing grain, hay, fruit and vegetables on the Eastern Shore of Maryland. Harvest on our farm begins in May and continues through November, and sometimes into December. Because of the number of crops we grow and the seasonality of those crops, we keep busy harvesting something like seven months out of the year.

In May we begin harvesting hay which continues through September depending on the year’s rainfall, which dictates how many times we can harvest a hay field. In June and July, we harvest barley, then wheat. In August, it's cannery tomatoes and fresh market green beans. In September, wine grapes and corn. Then, in September through early December, we continue to harvest corn and soybeans, including tofu or food-grade soybeans that we grow for regional Asian food processors in the D.C., Baltimore and Philadelphia area.

The family farm keeps us busy but is extremely rewarding. I wouldn’t want to raise my kids anywhere else but on a family farm. They understand birth and death, the benefits of hard work, and the togetherness of family at work and play.

Harvest to me is the summation of all of my family’s blood, sweat, and tears encapsulated into a season. Harvest is our collected prayers for Mother Nature to cooperate and send us rain when we need it, make hurricanes stay out in the Atlantic, and give us sunny days to dry hay and ripen grapes. Harvest is walking through the fields to check the crops and evaluate which varieties did well, and which we shouldn’t grow in the future.

Harvest is the desire to keep everyone on the farm safe, and hope that we will actually be able to spend some quality time together during the “slow” months of winter. Harvest is watching the fruits of our labor grow and produce food for the many. Harvest is reflecting on our land and soil stewardship each and every year, wanting to be sustainable both environmentally and economically, and leaving the farm in better condition than we received it.

Harvest is family, working side by side every day and still loving each other. Harvest is the full circle of life, every year, every day, the fruits of our sowing and reaping.