Wednesday, 15 April 2015

A Late Spring?

The spring has finally arrived after a fairly dry but chilly start to the year.  Rainfall totals for the farm, from the remote weather station indicated just over 100mm of rain since 1st January.  Soil temperatures, however have been really cold, only getting into the critical range for seed germination of between 7-8 degrees at the end of March.  Seeds will obviously germinate at lower temperatures but the emergence of the crop will be slower, leaving the seedlings exposed to pest (slug and pigeons) attack for a longer period of time.  An old saying that spring barley should be out of the bag and out of the ground in the same week should be remembered.  This is especially true for crops that are direct drilled in non-cultivated soils.  Cultivation warms up the soil by moving the soil, and can help dry out the soil to allow earlier plantings, but there are disadvantages.
By drying out the soil it leaves less moisture available to germinate the seeds especially if the weather turns warm and windy after the seeds have been planted.  It also risks smearing the soil at the lower depths, where the tine or disk is working, which means putting a deeper compaction layer in the soil. It also burns up the organic matter in the soil releasing carbon into the atmosphere.  I remember in spring 2013 we planted spring barley ahead of my Nuffield trip to Canada and three weeks later the seeds hadn't emerged, it was that cold.  It just goes to show that you can't farm by the calendar!
There is also a practical balance to think about as well, we can't justify having enough man and machinery power to drill everything on the perfect day, so we have to start when we can on the suitable fields in order to get the crops planted.  These are two pictures of beans (top) and peas (below), planted using a direct drill (no cultivation) system.  The peas have germinated and the roots have started to emerge within 3 days, which is great news.  The seedbed was moist and warm so crop establishment will be quick and will hopefully outgrow the early attack of marauding pigeons!  The beans were planted 10 days earlier, but germination was slower as the seed bed was cooler.  As the sun shines the soil will continue to warm up and it is important that these crops get away to the very best start to optimise their potential and deliver a good harvest in August.  There's a long way to go and we'll have to wait and see how the season develops.