Developing a practical guide to using the CSNT and ISNT for improved nitrogen balances on dairy farms

Developing a practical guide to using the CSNT and ISNT for improved nitrogen balances on dairy farms

Summary

This project, initiated by ideas from two dairy farmers, aims to identify a more practical and effective sampling process for two nitrogen management tools: the Illinois Soil Nitrogen Test (ISNT) and Corn Stalk Nitrate Test (CSNT).

With the continuing rise in crop input costs farm mangers are interested in tools that allow them to properly credit nutrients they have on the farm and minimizing purchased fertilizer. The ISNT and CSNT are tools that illustrate to farmers where they can make adjustments to N management on corn and minimize purchased inputs. While a growing number off farm managers see the value of the CSNT and ISNT information, they are interested in finding more efficient and lower cost methods to gather the samples and run the tests.

This project aims to address three practicality questions raised by farmers: (1) can CSNT samples be collected after harvest rather than walking through standing corn (time reduction); (2) can certain fields be targeted or should the whole farm be sampled; and (3) what is the cost of sample collection and testing compared to the benefits of reduced N fertilizer.

The goal is to develop a farmer-friendly approach to using the CSNT and ISNT, and materials (fact sheet, post cards, web articles). For the two farms in the project, all corn fields were sampled in fall 2011 with followup sampling for fields that remained in corn this fall 2012. Based on feedback from these and other farms, and a study to evaluate the impact of sampling protocol on CSNT values, a new protocol was developed and introduced at the 2012 NRCCA training held at the end of November, 2012, and attended by 73 certified crop advisors. The new protocol is documented in a new Agronomy Factsheet (Agronomy Fact Sheet # 72: Taking a Corn Stalk Nitrate Test Sample After Corn Silage Harvest, 11/21/2012) downloadable from our NMSP website: http://nmsp.cals.cornell.edu/publications/factsheets/factsheet72.pdf.

Farm data for both years are being evaluated and farm visits will take place early next year to evaluate objectives/questions 2 and 3 of the project.

Objectives/Performance Targets

Two local farms will work with campus staff to evaluate implementation protocols for the ISNT and the CSNT and develop a more farmer-friendly approach to assessing performance for whole farm N fertilizer and manure use decision making. Each farm team will compare targeted (some fields only) and whole farm (all fields) approaches to evaluate the effectiveness of the tool package in reducing risk of both over and under fertilization (i.e. in generating confidence that changes can be made). Each farm team together with the NMSP staff will conduct a cost/benefit analysis of different protocol approaches. The analysis will compare the cost of implementation, using both old and newly-adapted sampling and implementation strategies, to the fertilizer saving benefits realized using the information provided by the tests. The results of the three practicality studies will provide the guidance needed to develop a new sampling protocol that requires less labor but is still accurate and will allow greater adoption by other farms.

Accomplishments/Milestones

The corn fields of two local farms were sampled for ISNT and CSNT in fall of 2011 and resampled for CSNT (for those fields still in corn) in fall of 2012. Farmer meetings were held at the start of the project and once initial data were available (2011 results). Each farm team selected subsets of fields to be targeted to evaluate the effectiveness of the tool package in reducing risk of both over and under fertilization? (i.e. in generating confidence that changes can be made). We just compiled the 2012 dataset and will be meeting with the farms in January/February to evaluate the 2-year data and conduct a cost/benefit analysis of different protocol approaches.

A new CSNT sampling protocol was developed and introduced to facilitate sampling after corn silage harvest (shorter stalks) as walking through standing corn was identified as a major deterrent to sampling fields for CSNT by the farm teams and others who sampled fields for CSNT this year (a little of 900 farmer samples were analyzed for CSNT this fall). Sampling protocols for ISNT remain the same; CSNT sampling post harvest can more easily be combined with ISNT sampling as well, reducing the overall time investment in sampling for both.

Impacts and Contributions/Outcomes

To date, the biggest impact is the development and release for use of an alternative sampling protocol for CSNT (post-harvest) this month. This is documented in a new Agronomy Factsheet: Taking CSNT samples after corn silage harvest (http://nmsp.cals.cornell.edu/publications/factsheets/factsheet72.pdf). In 2012, a little over 900 CSNT samples were sent in for analyses (standard method), reflecting a steady increase over the past several years (almost a doubling since last year), and illustrating that CSNT sampling has become a more general practice for corn growers in the state. The new protocol will allow for a greater number of samples to be taken as it saves time if samples can be taken using a 4-wheeler after silage harvest. The current dataset for the two farms in this project will allow us to evaluate year to year differences on a field by field basis as well as on a whole-farm (corn fields) basis. New approaches, consistent with the Adaptive Management approach recognized as an effective way to fine-tune management over time by NRCS, are being developed and discussed.

Collaborators: