Pasture cropping

Pasture cropping can provide good quality feed in tired, thinning pastures.

The traditional aim of pasture cropping is to sow temperate cereals (wheat, barley, triticale and oats) into summer active native pastures (for example, Red, Mitchell and Warrego grasses) to either:

• bulk pastures up with winter forage
• harvest for grain at the end of the growing season.

Where to consider pasture cropping

Rainfall

Pasture cropping is suited to areas that do not have a strong dominance of seasonal rainfall where pasture croppers can take advantage of rainfall at any time of the year.

In good years, mixed farmers undertaking pasture cropping can capitalise on rainfall to grow summer feed, autumn and temperate cereal forage and then lock up in late winter for a grain harvest or hay making. 

In years with less rainfall, winter cereals can simply be grazed out with production from forage only. Animals are then able to graze on summer pasture dependent on rainfall and pasture growth.

Soil

Pasture cropping is best suited to soils with low water holding capacity or the lighter soil types. This is because removal of the summer fallow does not largely affect crop production and in turn maintains groundcover on these fragile soils. These soils rarely sustain cropping phases for long periods due to inherent low fertility or low water storage capacity. 

Farmers are able to maintain or introduce perennial pastures to help maintain soil structure and ensure the long term health of the soil while also having the opportunity to make money from the pasture crop.

Pasture cropping system input vs yield

There are a number of successful pasture cropping systems with no “one-size-fits-all” technique used across every farm. 

When pasture cropping systems move outside of the ideal conditions for soil type and seasonal rainfall patterns that the largest limitations become apparent. Moisture and nutrients drive crop yields so growers thinking about pasture cropping should consider the impact this will have on their yields.

For example, Colin Seis is well known across Australia for his innovative pasture cropping techniques. He highlights the profitability of the system rather than high production levels. By using low rates of fertiliser and chemical, he has dropped his costs substantially with only a small reduction in his output. He is able to lower his use of knockdown chemical inputs by utilising high impact grazing to reduce biomass.

In work performed at Wellington, NSW, the wheat yield of pasture cropping was consistently lower than that of no-till cropping, with yields reduced by as much as half. This is due to competition of resources, namely nitrogen and moisture.

While crop yield will be lowered, the profitability of the entire system may be much higher. Farmers should also look at the value of grazing over summer and the forage from the winter cereal to their enterprises.

Annual legumes

Many extensive pasture systems contain the annual legumes subterranean clover or annual medics. While these are very high quality plants for livestock production, they have quite shallow root systems. This means that they often struggle during hot-dry periods in spring and may not recover and continue to grow if rainfall occurs later in spring.

Even in good growing conditions, subterranean clover and medics have usually reached their maximum production by mid spring and from then on, they begin to senesce and ultimately die off by late spring-early summer.

Some of the deeper rooted annual legumes such as biserrula, French serradella, yellow serradella and arrowleaf clover may fit very well in flexible crop-pasture rotations as they are:

• capable of surviving periodic dry spells often experienced in spring and then being able to respond to later spring rainfall.
• more reliable in setting seed and therefore in regenerating reliably in following years.

The ability to recommence growth following a dry spell also means provision of higher quality green forage for livestock later in the spring-early summer period which can result in higher levels of livestock production.

Important considerations for your enterprise

Fertiliser

While some pasture croppers choose to limit fertiliser inputs, be conscious of the nutrient removal of your enterprise. 

For every dry matter (DM) tonne of grain or hay harvested per hectare, around 2-3 kg of Phosphorous (P) is also removed in addition to other nutrients like Nitrogen (N) and Sulfur (S). 

Sowing implement 

Disk-seeders that offer minimal soil disturbance are advised however very narrow points or “lucerne renovators” can also be used on direct drill, tined implements. This reduced soil disturbance results in less damage to the perennial pasture species and improved growth rates.

Herbicide

Without high density grazing at your disposal, knockdown herbicides (paraquat/diquat or low rates of glyphosate) will need to be used where high densities of winter annual weeds are germinating. 

Damage to the summer perennials can be minimised by using these knockdowns during the cold winter months when these plants have shut down and growth rates are slow.  Winter annuals will compete heavily with the sown crop and reduce grazing quality and virtually eliminate any chance of a grain harvest. Post-emergent grass sprays may need to be utilised as well.

Soil carbon levels

Another benefit of the pasture cropping system is the increased soil carbon levels as a result of maintaining more biomass in the cropping system. 

Pasture cropped systems have similar soil organic matter levels to that of perennial pasture only systems, which are higher than cropping only soil systems. This added soil carbon, which is built up over years of practising pasture cropping, results in increased nutrient and moisture holding capacity.

As a rule, each 1% increase in soil organic carbon increases water holding capacity of soils by around 2%. In dryland situations, around 2% organic carbon levels is considered optimal.

Groundcover

Low levels of groundcover and exposed topsoil can lead to wind and water erosion, a reduction in soil water storage and poor water infiltration. A significant proportion of plant nutrients are found in the topsoil which can then be lost through erosion.

Groundcover slows runoff and evaporation which increases water infiltration and soil water storage. Groundcover also protects surface soil from raindrop impact preventing the breakdown of soil aggregates which in turn increases infiltration.

At best approximately 25% of fallow rain is stored in the soil profile and while the percentage stored is highly variable a lack of groundcover will reduce storage efficiency significantly. At 10% groundcover an average fallow efficiency of 15% can be expected and at 50% groundcover approximately 20% fallow efficiency.

Groundcover levels of 70% are needed to obtain 25% fallow efficiency.

The organic matter that makes up groundcover also supports a diversity of microflora that can have both positive and negative impacts on following crops and pastures.

Low levels of groundcover will significantly reduce productivity when the drought breaks as water storage will be reduced and this will be reflected in crop and pasture productivity. Where groundcover levels have fallen below 30% and stored soil water is insufficient to plant a cash crop managers may consider the sowing of cover crops if a planting opportunity arises.

Assessing if pasture cropping may suit you

It is important farmers are aware of the best situations to employ pasture cropping, as their situations may be different. Pasture cropping is an incredibly complex system with many factors to consider when making the decision to implement. 

It is important to do your own research and talk to your trusted advisors before making any decisions.  You can contact Local Land Services to learn more about pasture cropping and how it could fit into your enterprise mix.

The examples below show situations where pasture cropping was considered.

Sheep enterprise with rotational grazing

A 40 ha paddock near Condobolin on light soils with some granite ridges has been a native pasture for 10 years and uncultivated. Following excellent growth over summer there were few winter annuals germinating, even after 100 mm of rain in March. Sheep were grazing the paddock but with an option to be rotated to a different paddock.

Assessment: This paddock would make an ideal candidate for pasture cropping. 

Actions: Sowing a grazing cereal will allow grazing over winter with the option to lock up for grain. The paddock is also small enough that it can be effectively grazed. Nutrient levels may be low, particularly N and P, so a soil test would be advised. Considering the summer growth of the paddock, there may be low levels of stored soil moisture. Investigation with a soil push probe to determine available water for a winter cereal crop is also advised.

Poor quality paddock following drought

A 250 ha, long-term cropping paddock on heavy soil at Warren had one fallow spray after summer rainfall. There were some perennial summer grasses, mostly windmill grass and Feather Top Rhodes grass, with high densities of annual ryegrass and barley grass germinating at the moment. The farmer has very few livestock left after the drought.

Assessment: This paddock would make a poor pasture cropping candidate. Poor quality summer perennials mixed with high growth of winter annuals negate the benefits of pasture cropping with a dual purpose grazing crop. 

Actions: If finding it hard to source knockdown chemicals, the farmer may consider a strategic cultivation to remove summer perennials as well as kill germinating winter annuals. Alternatively, leaving paddock fallow with a knockdown spray when winter grasses flower in spring is another option.

Patchy lucerne paddock

A 15ha lucerne paddock along the river near Dunedoo had been affected by the drought and had failed to respond after recent rain. While the lucerne stand was good in patches, other areas had died off. The farmer was worried about large bare patches becoming weedy.

Assessment: An excellent candidate for “sod seeding” or pasture cropping. 

Actions: Lucerne should be grazed heavily before sowing with an application of paraquat/diquat to kill annual weeds before sowing. High N levels from the lucerne pasture, assuming adequate rhizobium nodulation, will result in high biomass production from a winter cereal meaning good grazing potential. 

If the season looks likely to cut out from lack of moisture, the high biomass production of the cereal coupled with the quality lucerne will make very good quality mixed hay. Winter cereal will also provide competition against weed encroachment. Establishment of the cereal in the areas thick with lucerne due to competition may be a problem and again, use soil push probes to determine available soil moisture.