A common practice in the U.S. Midwest is to combine the quantities of phosphorus (P) and potassium (K) recommended for both corn and soybean crops into a single application. This biennial application of fertilizer is usually applied after soybean harvest. In a corn/soybean rotation, this results in a “direct” application to corn and a “residual” application to soybeans. Less common, although also studied by scientists, has been a biennial application applied after corn, resulting in a direct application to soybeans and a residual application to corn.
California farmers deal with complex irrigation and fertilization requirements of "specialty" crops within diverse rotations. Some of these so-called specialty crops have a farm value of more than $4 billion per year. These high-value crops demand careful management of both water and nutrients to achieve high yield and consistently high quality.
The 4R program still is and will continue to be a very important program for the crop nutrition industry.
Will it work for me? This question echoes in our minds as we sit through presentations at meetings, read news releases and listen to farm broadcasts. There's a lot of information out there about new practices and products. How much of what is offered will really make a difference?
Accommodating and instituting best management practices to achieve this pivotal component of nutrient stewardship seems simple enough. But dive into the intricacies associated with sourcing the perfect nutrient for each situation, and you'll find that maybe even the most seasoned grower could glean a couple tips from a holistic look at nutrient source selection.
"When you look at plant roots and consider that, for example, a nutrient like phosphorus is very critical for early seedling nutrition, you should also consider the direction the corn roots go - they tend to go out and downward at a 45-degree angle.
To say Dr. Tom Bruulsema wrote the book on 4R Nutrient Stewardship isn't much of a stretch. In 1994, Dr. Bruulsema joined the Potash & Phosphate Institute, which in 2007 became the International Plant Nutrition Institute (IPNI). Based in Guelph, Ontario, Canada, Bruulsema has helped spearhead the development of the 4R Nutrient Stewardship concept, including the coediting of the IPNI 4R Plant Nutrition manual.
When it comes to the 4Rs of crop nutrition (right source, right rate, right time, right place), many farmers focus most of their attention on right rate. The 4Rs should be thought of as a system that intertwines and works together to create a well-managed crop nutrition program. Four International Plant Nutrition Institute (IPNI) experts offer helpful insights to better achieve each R.
A thorough understanding of spatial variability in agricultural fields can influence many aspects of nutrient management. Whether it’s what nutrient source to apply, what rate to use, when to make the fertilizer application or what placement method to employ, understanding spatial variability can help growers, advisers, industry and policymakers contribute to more efficient and effective fertilizer management.
The right time to take soil samples is in rhythm with the crop rotation. Normally it’s best to sample following back-to-back plantings of the same crop, which creates a consistent basis for comparing fields and picking out trends over time. Most samples are taken in late summer and fall to allow ample time for planning a crop nutrition program based on the 4Rs of Nutrient Stewardship — applying the right nutrient source, at the right rate, time and place. But, in a drought, is fall sampling still a good idea? Yes. And the facts support it.
I no longer qualify for the “early career professionals” demographic or the much-catered-to Millennials club. However, as a Baby Boomer, my “senior” perspective does provide an opportunity to observe what in fact stands the test of time across the decades, whether for social issues or for basic principles of crop management.
Have you ever seen a soybean field where aphids infested some areas more than others? There’s a good chance the pattern might follow potassium (K) availability. Research conducted around ten years ago in Wisconsin and Michigan studied this phenomenon in detail.