Background

Since its introduction in the late 1980’s, Intensive wheat management has contributed to a doubling of the Kentucky average state yield (reference USDA state wheat statistics) while states such as Kansas remain almost stagnant. When asked, many Kentucky producers suggest that there are at least 3 factors which contributed to the majority of the yield increases, these include the following:

Head populations of 550-650 per square yard allowed this 220 acre Kentucky field to average over 100 bu/ac with 3 plots entered in a yield contest which all exceeded 115bu/ac. Prior to the introduction of intensive wheat management, most fields yielded from 30-60 bu/ac.

Stand Uniformity: Improved seeding equipment and greater attention to detail with regards to varieties, seeding rates, seed treatments etc. Many producers have now switched to no-till, a practice which can boost profits by trimming equipment costs, but it took a number of years of co-operative research in conjunction with the University of Kentucky to prove the viability of the system and to establish which management practices needed to be changed when a producer switched from conventional tillage to no-till. Insect and Disease Management. Prior to the adoption of intensive wheat management, many producers planted their crop in the fall and fertilized it one time in the spring. If weeds were a problem, many producers even mixed liquid nitrogen and a herbicide together to save a pass across the field, a practice which was unheard of in many European countries on account of crop damage and antagonism, especially at critical grain site initiation stages in the early spring. No fungicides or insecticides were utilized to manage these yield reducing problems. Nitrogen Forms, Rates and Timings: There is a now a significantly higher understanding of tiller densities and specific nitrogen timings at the grower level. In this regard, producers now understand how much N should be applied at which stage, to manipulate tiller populations and manage final head populations at harvest. Also improved nitrogen delivery uniformity has become very important (almost all KY producers utilize liquid nitrogen for their wheat nitrogen applications, especially for the 2nd application in the spring). Properly equipped liquid nitrogen application equipment allows almost perfect uniformity of nitrogen, which is difficult to match with other N sources. Many producers have found that liquid nitrogen provides the highest yields, and research from Ontario reinforces this observation. Ontario: Nitrogen Sources For Wheat.

The Problem

Some producers still apply liquid nitrogen to wheat in the spring with flat fan or flood-jet nozzles. Even when the wheat is small in the early spring, significant levels of leaf injury can occur. Leaf scorch causes infection sites for foliar diseases and reduces early spring plant health which is critical to the grain site formation process. Yield reductions of sprayed liquid nitrogen applications vary by conditions and nitrogen rates, but 5-10 bu/ac yield losses have been frequently documented. Additional plant injury and yield losses occur when liquid nitrogen and herbicides (especially SU herbicides) are tank mixed and sprayed on cereals in the spring. This practice should be avoided, in fact many producers should consider applying their herbicides in the fall to remove weed pressures before they begin competing with the crop in the spring.

Liquid nitrogen was sprayed on this field of wheat early in the spring with flat-fan nozzles. Plant health was significantly compromised at a time when yields are being determined.

While 3 hole nozzles are an improvement over flat fan spray tips, they do not apply nitrogen as evenly or accurately as a stream bar. 3 hole caps produce a triangular shaped distribution pattern that’s very height sensitive. As the boom raises up, two streams come together to deliver a 2X N rate as illustrated in the image to the right. As the boom is lowered (either intentionally on unintentionally on rolling ground), there may be areas that don’t receive any N, as illustrated in the second image to the right. With N prices at record levels, you need to apply the nutrient evenly so each plant receives a consistent quantity, 3 hole caps don’t allow this to happen. Three hole nozzles are also influenced by forward speed and/or wind speed. As producers buy larger and more powerful sprayers, they want to run faster. The pattern produced from the 3 hole caps narrows as effective forward speed increases, so constant changes in boom height are required to compensate for the changing distribution angles.

The photo left, illustrates a wheat field which had liquid nitrogen applied using three hole fertilizer caps. The photo below left, also illustrates a field that had a single application of N delivered with the 3 hole nozzles just prior to green-up. The N was the only application that was made at a 90 degree angle to the drill rows, so the streaks could be easily traced back to the 3 hole nozzles on the 120' boom. The photo below illustrates a couple of the main stem wheat heads which came from the previously discussed photo. The one on the left came from one of the yellow N deficient streaks and the larger head on the right came from one of the green streaks. Look at the difference in head size and flag leaf health. Based upon spikelet counts, we suggested that yields were halved in the streaks where little to no N was applied. There are lots of opportunities to increase wheat yields, don’t let poor N distribution be one of the weak links.

Multi-hole caps produce smaller droplets than a stream bar, this results in more leaf retention on the wheat and additional leaf tissue injury. Research shows that leaf injury translates into yield loss. As illustrated in the photo to the right, streams of nitrogen also collide when using the multi-hole caps, which further adds to the leaf injury problems.

Multi-hole caps are height dependant. When operating on rolling ground, it’s difficult to hold the boom at a consistent height above the crop. Height variations can result in 2-3 streams hitting the ground in the same area, which also results in 10-15” areas of the ground which receive no nitrogen at all. As expensive as nitrogen is, it must be applied accurately and uniformly. A set of multi-hole caps don’t achieve this goal.

The Solution

Most producers or dealers own mounted, trailed or self-propelled sprayers. Most of these sprayers can be equipped with stream bars to allow accurate and uniform liquid fertilizer application. We sell stream bars for many different brands and configurations of sprayers around the world and some are illustrated below. If you have questions regarding specific configurations, please call or email us.

When you order stream bars, we will need to know the following information to help us determine the optimal configuration and maintain the ideal application rate and pressure range.

• Nozzle spacing: (15” or 20” for example)
• Spraying speed: (We need an approximate operating speed range, for example 10-12mph)
• Application Rate Range: (For example, 12-20 gallons per acre of 28% nitrogen)
• Sprayer Plumbing Brand: (For example, Spraying Systems, Hardi, etc)

Benefits Of Stream Bars

• Accuracy Stream bars are designed to evenly apply liquid fertilizers such as 28%, 30% or 32% nitrogen to wheat and other crops. Each of the four outlets on the stream bars are ported to ensure consistent delivery of fertilizer over the range of operating pressures.
• Excellent for no-till  Stream bars deliver concentrated streams at equal distances, minimizing the amount of N tied up on residue, compared to the 3 hole nozzles (and especially flat fan nozzles) which increase the coverage on surface residue (in addition to the wheat leaves). 3 hole nozzles (and flat fan nozzles) also increase the amount of N which is tied up on surface residue and also potentially increase the N losses via volatilization.
• Unaffected by boom height Stream bars produce vertical streams of fertilizer with no overlap, so product application is unaffected by boom height.
• Minimal leaf scorch Stream bars deliver streams of fertilizer, so contact with the crop is minimized. High rates of nitrogen can be applied in one pass with minimal leaf injury, even on windy days.
• Available for 15” and 20” spacing Stream bars are available to fit most sprayers around the world and are available in 15” and 20” spacing.
• Adaptable for different product rates By using orifices, the operating sprayer pressure can be maintained within the 25 to 50psi range.

Stream bars provide uniform delivery of fertilizer despite windy conditions or rolling ground.

Growers with wet soils in the early spring, should consider wider tires or floater tires to enable them to apply nitrogen in a timely fashion.
Stream bars are available in 15” or 20” spacing to maximize yields.

Contact Phil at Needham Ag Technologies to order or request additional information:
270-785-0999 or by email at phil@needhamag.com