Do you get ALL the rain?
By Kim Deans
Are you obsessed with the weather? Is how much rain you got, or how dry it is frequently the first topic of conversation? This is a common affliction for those of us who manage land. We live intrinsically attuned to the weather and the cycles of the seasons. It is rare to meet a farmer or rancher who does not diligently record their rainfall. In a group of farmers I worked with a few years ago, a group member who was a new property owner and recently moved to our district from the city was amazed to hear how ALL of the other farmers in the group kept rainfall records. This was such a foreign concept to her, yet those of us born and bred on the land do this without questioning it.
We clearly acknowledge the role that the amount and timing of rainfall plays in the profitability of our business as farmers. We always know how much rain has fallen into our rain gauge. Yet how many of us know how effectively we make use of the rain that falls on our landscape? Rainfall provides us with valuable water essential to our farming system, and to life, for free. Rainfall is widely recognised as a key driver of farm profit as well as being a key driver of farm losses when we fail to receive enough rain or when we receive rain in excess or at the wrong time.
Given this obviously strong relationship of rainfall to profit why is rainfall use efficiency not the number one priority for all land managers? Even when we pay a high price for water in irrigated systems we still see soils that struggle to absorb and store valuable moisture for plant growth to make the most efficient use of this precious resource. Often when we pay for something we value it more highly, yet this does not seem evident with respect to irrigation water, which is commonly stored in bulk in dams where lots of it gets lost to evaporation.
Rainfall use efficiency investigations undertaken on 1700 farms in northern NSW Australia (2012, Gardiner & Gammie) found rainfall use efficiency varied from 6% to 70% with an average of just 21%. This clearly shows plenty of room for improvement. It is highly likely that this is far worse now. Industrial agricultural practices such as clearing, burning, cultivation, synthetic fertilisers, pesticides, over grazing, bare chemical fallows and the like have depleted the carbon in our soils. Our soils have structurally collapsed and these degraded soils cannot absorb water when it rains. Water either runs off creating erosion and increasing the incidence of flooding, or the water sits on the soil surface, unable to infiltrate into the soil until it is lost to the system due to evaporation. With the water cycle broken, soils get progressively drier and we effectively create our own droughts. Here in Australia we have a notoriously variable climate with frequent dry spells so why do we continue with agricultural practices that make matters even worse?
It seems that by resigning ourselves to the fact that we can’t control the weather and influence how much rain we receive we have forgotten to look for the aspects of the water cycle that are within our control as land managers. Our land management can influence soil health through rebuilding soil carbon, improving the ability of our soils to absorb water when it rains and store this water for plant growth. With every 1% of soil carbon we can store an additional 144,000 litres per hectare of water EVERY time it rains! We can reduce losses of water due to evaporation and run off by keeping soils covered at all times. Drought does not create bare ground, our management does. Even if we captured just half of the water that is currently evaporating think about how much more resilience to droughts we would have!
The value of managing land to conserve water in our landscapes is clear when you consider climate data. Table 1 shows climate data gathered from the Bureau of Meteorology in Australia for locations in 5 states to demonstrate average pan evaporation measurements as compared to average annual rainfall. In every case evaporation is higher than rainfall. If we want to maximize farm profits, and reduce the impact of climate variability then focusing on reducing water losses to evaporation through improved soil health is crucial and this is within our control.
Climate Figures obtained from Bureau of Meteorology.
Rockhampton QLD: 815mm average rainfall, 2112mm average evaporation
Armidale NSW: 724mm average rainfall, 1139mm average evaporation
Longerenong VIC: 415mm average rainfall, 1566 average evaporation
Adelaide SA: 547mm average rainfall, 1467mm average evaporation
Esperance WA: 618mm average rainfall, 1638mm average evaporation
Managing to improve rainfall use efficiency includes focusing on
Maintaining living ground cover
Growing a diverse range of annual and perennial plants to enable rain to be used when it falls
Managing for high soil organic matter
Nurturing soil biological activity to maintain soil health
Avoiding practices that lead to compaction
Improving soil structure
Slowing transpiration by maintaining shelter
Matching land use to land capability
Protecting riparian areas
What we measure we can manage and improve, what doesn’t get measured, managed or improved generally contributes to a growing list of unintended consequences in farming ecosystems that quietly compound out of sight and out of mind until a major catastrophe brings our attention to them. Here in Australia record breaking drought and wild fires are screaming at us to pay attention to the water cycle.
Start paying attention to the water cycle in your landscape by measuring and recording water infiltration rates for your soil. You can find instructions for this simple test here. I also encourage land managers to take those rainfall charts and start to record the production you are achieving in your business per millimetre of rain. Keep it simple. Work out the most appropriate time period for rainfall to contribute to your profit and watch the trend of gross margins and whole farm profit per millimetre of rain over time. Track this in line with your regenerative farming practices and over time this will tell you if your land management practices are taking you where you want to go.
With the focus all agricultural land managers have on rainfall, nothing will speak more loudly about the benefits of regenerative farming practices, and improve the rate of adoption of these methods, than becoming living proof that regenerative farmers get ALL the rain.