Catch crops or green cover have received a lot of debate and discussion in the past, year due mainly to the options to grow them either with greening or under a GLAS scheme. Catch crops, also called green cover, are defined as autumn cover crops that are used to take up plant nutrients that might otherwise be lost or leached into the environment.
Under current rules, catch crops can be planted in the autumn as an equivalence measure for crop diversification where a grower is only growing one arable crop despite having a greening obligation to grow two or more.
But using the equivalence measure requires that 100% of the crop area be planted to catch crops, which must be planted before 16 September and remain in place until 1 December. This effectively rules out this use in a winter cropping scenario. It is hoped that this may be changed to only 25% of the area for the 2016 application year.
Twenty-four growers are to avail of this equivalence option in 2015 but it is essential to be in GLAS to use it. Some farmers who wished to avail of this equivalence option did not apply to GLAS and so they cannot use this measure to substitute for having fewer crops than required.
For those who do avail of the option, a reduced payment applies to cover the cost.
The second option is to use cover crops as an option for generating additional income under GLAS while also improving the health of your soil. There is no limit as to how much one can sow but there is a limit on the maximum payment under GLAS (€5,000). Areas committed under this scheme will receive €155/ha to cover the seed and establishment costs.
The operating rules for this option are broadly similar to the equivalence option. A minimum of two different crops from a specified list must be planted.
The third option is for the grower who wants to put in catch crops for the benefit of the soil without any direct support for so doing. In these situations, the farmer has complete freedom to plant what he/she wants and to remove it whenever is appropriate. However, early planting must always be recommended to maximise the potential benefit to the soil and following crop.
Soil improvement
There are many potential benefits from planting of catch crops, but the main long-term benefit is soil improvement. These crops consume nutrients that might otherwise be lost, hold them over winter and recycle them again in the following spring or summer.
But as well as the nutrients, they provide valuable organic matter to the soil, which feeds the biological system, delivering knock-on benefits for soil fertility and soil structure through the creation of humus.
The benefits to the soil apply to both fertility and structure, according to Philip Reck who has been using catch or cover crops for a number of years on Walter Furlong’s farm in Wexford. A few weeks ago, Germinal Seeds and the Cooney Furlong group hosted a very interesting meeting on catch crops at which Philip outlined his experiences.
Planting
Most of the species to be planted as catch crops have small seeds and so require decent seedbeds to ensure good establishment and benefit. Under the GLAS scheme, one is not allowed to establish via ploughing, so some form of shallow cultivation must be used.
As a grower with considerable experience, Philip said that moisture can be an issue during the autumn sowing window. For this and other reasons, establishment must be rapid with minimal time between cultivation and rolling to help conserve moisture. These small seeds need good soil-seed contact and you must conserve soil moisture. “So after planting, one should roll, roll, roll,” Philip said.
He is using a single machine to disc the stubbles, broadcast the seed and roll the planted soil. Timeliness of planting is essential at that time of year as temperatures begin to drop off. “One day’s growth in August is equivalent to one week’s growth in September,” Philip stated, “but one day in July is equivalent to the whole month of growth in August.”
So timely planting is essential to maximise the benefits of catch crops and farmers must plan to get this operation done as quickly as possible. In some instances, this may require the chopping of straw, rather than its removal so as to help speed up planting from the end of August onwards. This may require a new discipline in order to get the most benefit from the practice.
“It is very important to get even establishment across the field as pests like slugs can be a problem if the autumn is wet,” Philip stated. But the light cultivation will bring about a bit of mineralisation of nitrogen, which helps. In general, the best cover crop growth brings the best following crop, Philip commented.
Philip has used a variety of crop mixtures so far but the main mix comprises tillage radish, peas and vetch. This produces a big canopy volume in the autumn and leaves an amount of nitrogen behind for the following crop. The complementary root systems help to break up the seedbed, leaving a tilth on top for the following crop. This means it can be easily cultivated for the following crop without ploughing as the tilth is already present. And the stubbles show good water percolation which helps timeliness.
Philip sprays off any remaining crop cover in springtime and when it’s time to plant he just runs a shallow disc across the top to break up the cover and then combine-drills seed and fertiliser into that. So, when done properly, it helps to decrease establishment costs.
Catch crops will benefit from the application of artificial fertiliser in the autumn but that would kind of defeat their purpose, which is to pick up nutrients in the soil to prevent them from being lost. This is especially the case within GLAS schemes but if one was growing a catch crop for grazing (fodder) then one is entitled to use a specified level of fertiliser.
Regardless of whether one uses fertiliser or not, the planting of a catch crop does not alter the specified nitrogen index, which is based on rotation, for the following crop.
Breeding objectives
Another speaker on the day was Jérôme Vasseur, a catch crop breeder from Jouffray-Drillaud in France. The company has a specific catch crop breeding section near Poitiers. Jérôme reminded us that the breeding of catch crops is similar to any other crop in that there are target objectives for each of the species.
He reminded us that different species have very different effects in the soil through their very varying root systems. He also spoke about the fact that certain species can have either positive or negative effects on the following crop. Work at Teagasc found a significant negative consequence where rye was used as the catch crop and its decaying vegetation could sometimes have a very negative effect on the growth of some following spring crops.
Jérôme added to this by stating that decaying brassica vegetation can sometimes have a serious detrimental effect on a following maize crop.
With catch crops, there are many objectives. Jerome indicated that earliness is a particularly important characteristic as these crops must grow rapidly and bulk up quickly to help maximise their benefit.
Seed size is also an issue, especially for some planting techniques, and so some crops are being bred for smaller seeds (for example, peas), while in vetches the target might be for bigger seeds. Being able to avoid extremes of size helps limit any seed segregation that might occur during planting. More uniform seed size helps one to work with a suitable single sowing depth.
Sensitivity to frost is also a breeding objective but this is not highly relevant to Ireland. Jérôme said many other interesting things about the varying families of crops that can be used for catch crops and about the differences than can exist within a species. I will carry more of his comments in a coming issue.
There are three main reasons why farmers could/should consider growing catch crops:
Full inversion tillage cannot be used for planting. Catch crops grown within GLAS must be planted before 16 September and remain in place until 1 December. Timeliness of planting is very important to secure good autumn growth levels.
Catch crops or green cover have received a lot of debate and discussion in the past, year due mainly to the options to grow them either with greening or under a GLAS scheme. Catch crops, also called green cover, are defined as autumn cover crops that are used to take up plant nutrients that might otherwise be lost or leached into the environment.
Under current rules, catch crops can be planted in the autumn as an equivalence measure for crop diversification where a grower is only growing one arable crop despite having a greening obligation to grow two or more.
But using the equivalence measure requires that 100% of the crop area be planted to catch crops, which must be planted before 16 September and remain in place until 1 December. This effectively rules out this use in a winter cropping scenario. It is hoped that this may be changed to only 25% of the area for the 2016 application year.
Twenty-four growers are to avail of this equivalence option in 2015 but it is essential to be in GLAS to use it. Some farmers who wished to avail of this equivalence option did not apply to GLAS and so they cannot use this measure to substitute for having fewer crops than required.
For those who do avail of the option, a reduced payment applies to cover the cost.
The second option is to use cover crops as an option for generating additional income under GLAS while also improving the health of your soil. There is no limit as to how much one can sow but there is a limit on the maximum payment under GLAS (€5,000). Areas committed under this scheme will receive €155/ha to cover the seed and establishment costs.
The operating rules for this option are broadly similar to the equivalence option. A minimum of two different crops from a specified list must be planted.
The third option is for the grower who wants to put in catch crops for the benefit of the soil without any direct support for so doing. In these situations, the farmer has complete freedom to plant what he/she wants and to remove it whenever is appropriate. However, early planting must always be recommended to maximise the potential benefit to the soil and following crop.
Soil improvement
There are many potential benefits from planting of catch crops, but the main long-term benefit is soil improvement. These crops consume nutrients that might otherwise be lost, hold them over winter and recycle them again in the following spring or summer.
But as well as the nutrients, they provide valuable organic matter to the soil, which feeds the biological system, delivering knock-on benefits for soil fertility and soil structure through the creation of humus.
The benefits to the soil apply to both fertility and structure, according to Philip Reck who has been using catch or cover crops for a number of years on Walter Furlong’s farm in Wexford. A few weeks ago, Germinal Seeds and the Cooney Furlong group hosted a very interesting meeting on catch crops at which Philip outlined his experiences.
Planting
Most of the species to be planted as catch crops have small seeds and so require decent seedbeds to ensure good establishment and benefit. Under the GLAS scheme, one is not allowed to establish via ploughing, so some form of shallow cultivation must be used.
As a grower with considerable experience, Philip said that moisture can be an issue during the autumn sowing window. For this and other reasons, establishment must be rapid with minimal time between cultivation and rolling to help conserve moisture. These small seeds need good soil-seed contact and you must conserve soil moisture. “So after planting, one should roll, roll, roll,” Philip said.
He is using a single machine to disc the stubbles, broadcast the seed and roll the planted soil. Timeliness of planting is essential at that time of year as temperatures begin to drop off. “One day’s growth in August is equivalent to one week’s growth in September,” Philip stated, “but one day in July is equivalent to the whole month of growth in August.”
So timely planting is essential to maximise the benefits of catch crops and farmers must plan to get this operation done as quickly as possible. In some instances, this may require the chopping of straw, rather than its removal so as to help speed up planting from the end of August onwards. This may require a new discipline in order to get the most benefit from the practice.
“It is very important to get even establishment across the field as pests like slugs can be a problem if the autumn is wet,” Philip stated. But the light cultivation will bring about a bit of mineralisation of nitrogen, which helps. In general, the best cover crop growth brings the best following crop, Philip commented.
Philip has used a variety of crop mixtures so far but the main mix comprises tillage radish, peas and vetch. This produces a big canopy volume in the autumn and leaves an amount of nitrogen behind for the following crop. The complementary root systems help to break up the seedbed, leaving a tilth on top for the following crop. This means it can be easily cultivated for the following crop without ploughing as the tilth is already present. And the stubbles show good water percolation which helps timeliness.
Philip sprays off any remaining crop cover in springtime and when it’s time to plant he just runs a shallow disc across the top to break up the cover and then combine-drills seed and fertiliser into that. So, when done properly, it helps to decrease establishment costs.
Catch crops will benefit from the application of artificial fertiliser in the autumn but that would kind of defeat their purpose, which is to pick up nutrients in the soil to prevent them from being lost. This is especially the case within GLAS schemes but if one was growing a catch crop for grazing (fodder) then one is entitled to use a specified level of fertiliser.
Regardless of whether one uses fertiliser or not, the planting of a catch crop does not alter the specified nitrogen index, which is based on rotation, for the following crop.
Breeding objectives
Another speaker on the day was Jérôme Vasseur, a catch crop breeder from Jouffray-Drillaud in France. The company has a specific catch crop breeding section near Poitiers. Jérôme reminded us that the breeding of catch crops is similar to any other crop in that there are target objectives for each of the species.
He reminded us that different species have very different effects in the soil through their very varying root systems. He also spoke about the fact that certain species can have either positive or negative effects on the following crop. Work at Teagasc found a significant negative consequence where rye was used as the catch crop and its decaying vegetation could sometimes have a very negative effect on the growth of some following spring crops.
Jérôme added to this by stating that decaying brassica vegetation can sometimes have a serious detrimental effect on a following maize crop.
With catch crops, there are many objectives. Jerome indicated that earliness is a particularly important characteristic as these crops must grow rapidly and bulk up quickly to help maximise their benefit.
Seed size is also an issue, especially for some planting techniques, and so some crops are being bred for smaller seeds (for example, peas), while in vetches the target might be for bigger seeds. Being able to avoid extremes of size helps limit any seed segregation that might occur during planting. More uniform seed size helps one to work with a suitable single sowing depth.
Sensitivity to frost is also a breeding objective but this is not highly relevant to Ireland. Jérôme said many other interesting things about the varying families of crops that can be used for catch crops and about the differences than can exist within a species. I will carry more of his comments in a coming issue.
There are three main reasons why farmers could/should consider growing catch crops:
Full inversion tillage cannot be used for planting. Catch crops grown within GLAS must be planted before 16 September and remain in place until 1 December. Timeliness of planting is very important to secure good autumn growth levels. 
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