For me personally, and I know many others, it was not greed or ego but FEAR to put on any more amt of fertilizer than for removal for planted year. Now I never in 45 years ever wanted to over apply fertilizer because of higher cost/acre which was more money borrowed (especially in years of 21% interest on production loans). Like most I k…
For me personally, and I know many others, it was not greed or ego but FEAR to put on any more amt of fertilizer than for removal for planted year. Now I never in 45 years ever wanted to over apply fertilizer because of higher cost/acre which was more money borrowed (especially in years of 21% interest on production loans). Like most I knew I put on what the University's recommended for projected yield. If had a farm that had been run down we would put a little more P & L on to do a slow rebuild. If didn't get tests up to at least medium, yield could suffer even though had same production costs/A. Several years ago I did soil testing for N early in season to see how much N there and make decisions. Then technology to test corn leaves in August to see why corn was turning brown, if no green-no photosynthesis. Low and behold corn was out of N, right at ear production time, bado, bado. Hadn't put enough on or lost it. Unfortunately the country has not addressed the nitrate problem for a long time. I remember when there were no subsidies and have always though all should be stopped cold. None for rice, wheat, corn, SB, tobacco, different nuts, etc. I can't imagine how few farming operations would be left, ya think there are big farms now!!!
Since Pine Lake in Hardin County is algae impaired due to excess phosphorus, 86% from farm field runoff (Pine Lake TMDL), Phosphorus has been my focus. Water samples taken at Lower Pine Lake by the IDNR show a rising trend (exceeding EPA lake recommendations 10 years ago) in dissolved P over the last 20 plus years. I've reviewed several hundred manure management plans filed at the Hardin County Court House which indicate crop utilization rates of 59pounds phosphorus utilization rate with a corresponding 179 pounds applied with the manure application. The corresponding P index calculation indicates the vast majority of field soil tests who STP in the high to very range. Conversations with local farmers suggest 100 pounds ommercial P is being applied but when asked what soil test P is, I get that's what the guy tells me I need. I've been asked many times, why would more be applied than what' is needed. This implies they are not but the data I have indicates they are.
You and I live in different parts of Iowa and have very different pictures of what's going on. It sounds like you are doing all the right things but paints a very different picture than the data shows I:m looking at. Be well my friend.
It is correct we live in different parts of Ia. 85% of applied phosphorus is attached to soil particles, soil must leave. With Washington Co being either #1 or 2 in no-till, which greatly reduces soil loss, could this be a factor in other areas? I don't disagree with your questioning of why applying more than removal if already having tests in VH range.
Here are links to ISU and K State addressing this subject. I modeled the P Index using Hardin County data from MMPs and found as P rises in soil above 40 ppm, the transport mechanism shifts from soil erosion to dissolved P. When using soil saving practices, no till, cover crops, buffer strips, even wetlands, P loss dropped quickly but then dissolved P rose over the next 10 to 20 years as soil test P rose with continued over application. This is what happened to Lake Erie in the 80s and 90s. Purdue USDA ARS has this well documented. Latest ISU and K State studies in the links below confirm this mechanism of P loss. In my mosel, applying P at the crop removal rate to achieve the optium levels would reduce P loss by 35 to 40 percent. This could be achieved by applying man;ure at the N rate but rotating fields over a 3 to 4 year basi with no P applied in the off years but of course commercial N applied in thos years as well. I hope these links work for you.
For me personally, and I know many others, it was not greed or ego but FEAR to put on any more amt of fertilizer than for removal for planted year. Now I never in 45 years ever wanted to over apply fertilizer because of higher cost/acre which was more money borrowed (especially in years of 21% interest on production loans). Like most I knew I put on what the University's recommended for projected yield. If had a farm that had been run down we would put a little more P & L on to do a slow rebuild. If didn't get tests up to at least medium, yield could suffer even though had same production costs/A. Several years ago I did soil testing for N early in season to see how much N there and make decisions. Then technology to test corn leaves in August to see why corn was turning brown, if no green-no photosynthesis. Low and behold corn was out of N, right at ear production time, bado, bado. Hadn't put enough on or lost it. Unfortunately the country has not addressed the nitrate problem for a long time. I remember when there were no subsidies and have always though all should be stopped cold. None for rice, wheat, corn, SB, tobacco, different nuts, etc. I can't imagine how few farming operations would be left, ya think there are big farms now!!!
Since Pine Lake in Hardin County is algae impaired due to excess phosphorus, 86% from farm field runoff (Pine Lake TMDL), Phosphorus has been my focus. Water samples taken at Lower Pine Lake by the IDNR show a rising trend (exceeding EPA lake recommendations 10 years ago) in dissolved P over the last 20 plus years. I've reviewed several hundred manure management plans filed at the Hardin County Court House which indicate crop utilization rates of 59pounds phosphorus utilization rate with a corresponding 179 pounds applied with the manure application. The corresponding P index calculation indicates the vast majority of field soil tests who STP in the high to very range. Conversations with local farmers suggest 100 pounds ommercial P is being applied but when asked what soil test P is, I get that's what the guy tells me I need. I've been asked many times, why would more be applied than what' is needed. This implies they are not but the data I have indicates they are.
You and I live in different parts of Iowa and have very different pictures of what's going on. It sounds like you are doing all the right things but paints a very different picture than the data shows I:m looking at. Be well my friend.
I deeply appreciate your correspondence and info you have researched and shared. It is encouraging me to dig deeper here. Thank you.
It is correct we live in different parts of Ia. 85% of applied phosphorus is attached to soil particles, soil must leave. With Washington Co being either #1 or 2 in no-till, which greatly reduces soil loss, could this be a factor in other areas? I don't disagree with your questioning of why applying more than removal if already having tests in VH range.
Here are links to ISU and K State addressing this subject. I modeled the P Index using Hardin County data from MMPs and found as P rises in soil above 40 ppm, the transport mechanism shifts from soil erosion to dissolved P. When using soil saving practices, no till, cover crops, buffer strips, even wetlands, P loss dropped quickly but then dissolved P rose over the next 10 to 20 years as soil test P rose with continued over application. This is what happened to Lake Erie in the 80s and 90s. Purdue USDA ARS has this well documented. Latest ISU and K State studies in the links below confirm this mechanism of P loss. In my mosel, applying P at the crop removal rate to achieve the optium levels would reduce P loss by 35 to 40 percent. This could be achieved by applying man;ure at the N rate but rotating fields over a 3 to 4 year basi with no P applied in the off years but of course commercial N applied in thos years as well. I hope these links work for you.
https://research.iastate.edu/2022/03/21/iowa-state-scientists-solving-the-complex-puzzle-of-dissolved-phosphorus-loss-from-farmland/
https://www.ksre.k-state.edu/news/stories/2021/08/agronomy-cover-crops-reducing-phosphorus-runoff.html#:~:text=But%20in%20something%20of%20a,loss%20are%20not%20a%20concern.