Here's a couple to get it started

New Year resolution, two thousand and ten,
It doesn't last long, and I don't know when,
But it'll get broken,
That word I have spoken,
The promise I made, I made it me sen.

New decade it is here, two thousand and ten,
Look back on the last, with excited news men,
Can't find much good news,
The last ten years with clues,
Glad it's all over, n' the last one for Benn.

Wheat below eighty again.

Ice wind from RPA men.

Two thousand and ten.

• Sorry it is not a limerick but as I started to type it just came out like this. 
•  
• Despite the snow of winter
• and the chilly grip of ice,
• Eternal springs my hope
• for snowdrops seek the light.
•  
• My thoughts then turn to Easter
• with cherry trees and thorn
• I'm glad for summer warmth
• of joy in being born.
•  
• The autumn of the year
• brings mellow fruitfullness
• and leafs ablaze of light 
• fore winter's cold distress.

TeslaCoils:

Wheat below eighty again.
Ice wind from RPA men.
Two thousand and ten.

Tesla,
You got the main germ of the limerick, just needs another couple of lines to help it flow.

Wheat below eighty Two thousand and ten,
Icy wind blowing from the RPA men,
All that we ask,
To be fare to our task,
Is to pay up more promptly and get rid of Benn.

Sorry, more of a haiku.

Try:

Another new year is turning,

To get in the field I'm yearning,

But I'd stop and I'd check it,

If I saw Margaret Beckett:

I wouldnt **** on her if she were burning.

on a similar vain:

Two thousand and ten starts muddy.

The prospects for farming are cruddy.

But I'd trample over fen,

To get close to Benn,

And make his face quite bloody.

a new year again, 2010.

you poms have that idiot hilary benn

his heids full o mince,,

his slavers make me wince,

but will the tories do better? ahem.

An election we'll have, two thousand and ten,
New set of leaders, with, a new set of men,
And women of course,
Who shout themselves horse,
N' get out of depression, all over agen. 

New Year resolution, two thousand and ten,
It doesn't last long, and I don't know when,
But it'll get broken,
That word I have spoken,
The promise I made, I made it me sen.

Now getting too old two, thousand and ten,
To ploughing match go, with other plough men,
Soft seat cushion needed,
The warnings are heeded,
Bad back and a chill, and then it's amen.

this the year 2010

sheep must be electronically tagged by then

the cause of this folly,

some eu wally

should be hung upsdide down  in a pig pen

And the reply: 

This tagging idea has clout.

"Why should we do it", you shout?

Easier to find them,

When some pikeys "hide" them,

And it might force some old buggers out.

In the year two thousand and ten.

Family farms shutting by the do-zen.

What will help this situation,

Is increasing world population.

Better get the wife pregnant again.

I'm really just doing my bit,

To help pig-men out of the *ahem* pit.

The best British meat,

Always tastes a treat,

Being slow-roast on a spit

The veggies and and RSPB,

On the other hand tend to disagree.

Eating lettice is alright,

But if it comes to a fight,

Us carnivores would win, we will see.

So compulsory reproduction's the craik,

But before we all jump in the (hessian or hay) sack.

Most farmers alive,

Are the wrong side of 55.

So try not to put out your back. (Do a risk assessment first).

But agricultural reproduction,

Is now science rather than function. 

Best keep on the good side of The Man,

And do a fertiliser managemant plan.

Or you'll really be up the junction.

in the year 2010,

we ve started lambing again.

they look so sweet,

cos they are worth more than wheat,

i think its time to get out of grain

 Allegedly reproduced from the unpublished secret diaries of Harriett Hurman covering the period when her husband was jailed in Tuscany for bribery, and the Secretary of State for Defra was preparing his memoirs for publication in the event that he lost his seat at the coming election.

It began in the year O Ten

my affair with that veggie O Benn.

But I  felt rather frantic and started to panic  

when he began to put paper to pen.