fertilizer or no fertilizer with peas

[shaller]

is it worth putting P, K and S with peas or will I get the same results with no fertilizer at all. some guys in this area say they are doing as good or better without.. HELP!!!

[buss]

Except for N, which has been shown by many to be unnecessary, the whole area of field pea fertilization with macro-nutrients remains controversial. The whole area is undergoing examination and, finally, the in-depth research that needs to be done is starting to get done. It will be some time before a clear picture emerges. Currently, the volume of research on pea fertility is very small compared to other crops. I have many clients who, like the people you've talked to, no longer add any fertilizer to their field peas. They seem satisfied with their yields although few have ever done any side by side comparisons. If one looks at the research literature, most of the work has been done with P. In the case of this nutrient, yield responses, even in situations when the soil tested as being deficient in P, were not nearly as frequent as in the case of wheat and canola. Yield responses, when they did occur however, were usually large enough to be profitable. Field peas clearly need P but we do not fully understand how they extract nutrition from the soil. Some have suggested that the process of N-fixation lowers the pH on root surfaces which encourages P-mineralization. This idea is still being investigated. Clearly we do not understand the process. One thing I've found is that many of my clients who have dropped fertilizing peas are heavy fertilizer users, espcecially for P, in the rest of their rotation. Especially after dry years, they may have 50 or 60 lbs/acre of available P in their soils. It is doubtful that one would get a field pea response to added P in such a situation. We used to think that for every 10 bu of peas, you would need about 8lbs of avialable P per acre. This assumption is now being challenged as well. Some have also reported that the response to added P goes down as the number of times peas have been grown on a specific field goes up. Frequency of the crop lowers response to added P. However, this is testimonial and I have not seen research backing this up. As to K and S, while they are both important nutrients, very little research has been done with them. In the fertility work that has been done, few yield responses have been noted. Again, we really don't understand the science of field pea fertility as well as we thought we did. Another point to consider - I've found that some growers experience better yields without fertilizer because they were seed placing large amounts of fertilizer. Taking away the fertilizer prevented plant injury even though the nutritional needs of the plant may have not been addressed. Still another point - in the area where I work, the chances of getting enough rain to actually exploit most of the yield potential of current varieites only occurs about 25% of the time. Less rain means less production and so less fertility needed. I expect that in years where we have more optimum conditions, fertility would become a more limiting production factor. In the end, I can't give you a straight yes or no answer but I can say that fertility responses are less frequent and more unpredictable in peas. I would advise soil testing before peas to see what you've already got and trying some various fertility levels on your farm to see what happens. I would also suggest considering your soil fertility situation over your whole rotation. Are you putting in so much fertility in other parts of the rotation that it becomes unnecessary when peas are grown or does the fertility you put down with your peas actually help other crops in the rotation. For instance, I have clients who have had canola crops benefit from the elemental sulphur they had applied in previous years with their peas. Sorry for going on so long but this a complex situation with a real lack of research supporting it at this point. I look forward to comments on this topic.

[oilcan]

After soil testing we've found under irrigation that fertilization is most beneficial in the production of seed peas.