It Pays to Manage Nitrogen Using Precision Agriculture Techniques
Productivity level “Management Zones” enhances
net dollar returns and nitrogen use efficiency.
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Figure 3. An example of “Management zone” delineated on a farmer’s field in northeastern Colorado. |
Recent increase in N fertilizer prices would result in increased production costs to producers. As the price of natural gas
rises, N fertilizer will undoubtedly follow the same trend. These increases in N fertilizer prices create hard decisions for producers. However, the current challenge could be viewed as an opportunity to be creative in ways that would boost net dollar return by enhancing the N fertilizer use efficiency and optimizing yields.
The implementation of precision fertilizer management techniques provides an opportunity to increase net dollar return while enhancing N fertilizer use efficiency through the identification of production level “management zones”. Management zones are sub-regions of the field that are similar in productivity potential. We all know by experience that grain yields harvested from different areas of a field are not uniform. Through our research over the last several years [research conducted by scientists from Colorado State University (CSU) and USDA-ARS] we have been able to develop a technique to divide fields into different sections or areas, called “productivity level management zones”. Management zones can be identified based on the following information:
1. Aerial imagery of bare soil and other stable soil properties,
such as soil organic matter content,
2. Topography of the field, and
3. Farmer’s personal experience and grain yield history across
the field.
Using this method we can divide fields into at least three different
management zones, “High, Medium, and Low” based on the
productivity potential of these areas, as shown in
Figure
3.
Our study over two years (Table
2) clearly demonstrates the economic
advantage of utilizing the management zone approach to manage N
fertilizer. The management zone approach optimized N fertilizer
applications across the field and at the same time enhanced the
net dollar return to the land and management, as presented in Table
2.
Optimizing N fertilization means that the areas of the field
that traditionally yield high would get a high N rate, medium productivity
areas would receive a medium N rate and low producing areas would
receive a low N rate. This insures that N use will be maximized
and the crop will have adequate N to optimize yield across the entire
field. It can also reduce the total amount of N applied without
affecting yields. In some cases, grain yields may even increase
using the management zone approach (Table 2) because higher N rates
are applied to those areas of the field with higher yield potential.
On-farm research conducted in Colorado has proven that these management
zones are real, and there are significant differences in grain yield
across management zones. Therefore, such an approach may reduce
N fertilizer costs. In the two fields shown in Table 2, we were
able to decrease the average N application rate across the field
by 30 to 40 lb N/Acre while increasing net return by $11-12/Acre.
Although the management zone concept presents itself as a positive response to higher N prices, there are also other considerations. Precision fertilizer management may require more time and planning by the producer. Also, there may be start-up costs associated with this management practice. Growers will have to look hard at the cost/benefit issues associated with precision fertilizer management that are specific to their farm operation and compare it to their current situation. Some presume that the hike in N fertilizer is temporary in nature and as natural gas supply increases, costs will decrease. Therefore, why adopt a new management strategy that may require more management input? This is a valid concern. However, adoption of precision fertilizer management will prepare the grower for current and future price increase in N fertilizer while enhancing N use efficiency. By beginning to adopt this new management practice now, a grower can reduce inputs, save money, and plan for the future.
