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Over the Hedge - Arable Barometer farmers' diary

Wet thwarts progress in Kent

I don't know if I dare I say it, but with the oilseed rape extending rapidly the pigeon wars seem to be abating slightly, writes Andy Barr from East Lenham Farm, near Maidstone.

Mind you I spoke recently to someone farming several thousand acres who had 14 gas guns deployed and was using a box of rope bangers every day, so I suppose I've had it easy really.

The Tipple barley turned a nice shade of grey in freezing winds over the Easter weekend but now looks healthier again, so I'm keen to put the last nitrogen on and am hoping to do the same to the oilseed rape before it's too tall.

I also have wheat T0 fungicides and nutrients ready to go and even have a little bit of spring rape to put in. But everywhere is very, very wet.

I am in a Nitrate Vulnerable Zone (it irks me a little that some of my field boundaries form the NVZ boundary) and carefully worked out my total nitrogen doses using the Planet software.

You probably won't be surprised to hear that I had concerns over the 180 kg/ha recommended for wheat after oilseed rape on what is potentially my highest yielding bit of land.

I duly had a couple of soil N tests done predicting that I could use the outcome to justify a higher input. The result? A potential supply of 136 kg/ha of N.

Why, I'm not sure. Maybe it's the result of sewage sludge applied two years ago, and/or very shallow tillage for seven seasons.

Although they are of disputed worth, I have had such tests done for several years and have never had such a high result in a continuous arable situation, sludge or no sludge.

So if I had started off wanting to apply 220 kg/ha of N, and then followed TAG's advice of taking off one kilogram of N from the fertiliser applied for every kilogram the test reads over 100 kg/ha, that would leave a revised recommendation of 184 kg/ha - very close to the Planet figure.

Perhaps there is something in this RB209 after all!

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Comments

 

TeslaCoils said:

Congrats on having so much N in the soil. We tested some land which is wheat after beans and there was under 20kg availiable - thats on heavy land in a completely non-inversion system, straw put back in the lot. Gah. Good saving at todays money.

How much N is your rape getting?

March 31, 2008 8:41 PM
 

barr said:

Well the previous rape had 190 kg N / ha. The soil is not heavy, more medium - chalky clay loam changing to silty clay loam. Its hard to understand why your situation should give under 20kg and mine over 130 - you 've probably got heavier land and after beans as well and similar cultivations. I have heard that the same sample sent to different labs have come back with different results, which is obviously not very helpful! Unless there are any other factors - rainfall some effect but as mentioned above its pretty wet here( usually we average about 710 mm / year).

April 3, 2008 9:23 AM
 

tiza said:

How many samples where taken over what area.

Where they core samples from surface to 90 cm

How quickly where the samples chilled and kept away from light and air.

How long a time elapsed between sampling and lab analysis.

Which method was used to calculate soil N

Have you any tissue anlysis of crop.

Without the above it is a pure lottery.

April 4, 2008 5:54 AM
 

barr said:

Well it was a local soil analysis company called Farm Image. I'm aware of the issues of quick chilling and testing etc. and I do trust they know what they're doing.

I have to say I'm wondering if it is any use or just a "lottery" as you say. Is it really only an exercise for justifying inputs on paper or can it be of real agronomic use if done properly? What do you think?

Also can you explain more to me about how the tissue analysis would compliment the results and which method you favour to calculate soil N?

Thanks

April 8, 2008 9:24 AM
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