April 7, 2020
April 6, 2020
Many parts of the world face water shortage and drought. As a result, farms and orchards are losing their capacity to produce food. According to the Food and Agriculture Organization (FAO), drought cost the world 29 billion USD in 2018; therefore, it is imperative for governments, crop consultants, and farmers to be proactive. Technology is already available for risk assessment, planning, and adapting land to drought. Among them are many small, inexpensive, and portable tools that can help make agriculture and forestry sustainable in these difficult times.
The drought that concerns farmers and horticulturists is agricultural drought. It starts with scarce rains, which lowers the water table and decreases water in rivers and lakes. People make the situation worse by overusing and depleting groundwater reservoirs. Demand for more water comes from increasing agriculture and forestry, as well as a growing population. As a result, this further reduces the water available for growing crops.
Also, climate change makes the scarcity of water worldwide worse. Global warming is causing more extreme weather events, making rain and storms stronger in some places and droughts more frequent and severe in other places. So, semi-arid and arid regions are becoming drier. (See Fig 1 for areas that are predicted to face droughts).
Figure 1: Map of areas facing drought hazard. (Image credits: Carrao et al. 2016, https://doi.org/10.1016/j.gloenvcha.2016.04.012)
According to the United Nations Convention to Combat Desertification, drought has been partly responsible for turning 12 million hectares of land barren, resulting in a loss of 20 million tons of grains.
Besides agriculture, forestry is also affected by drought. However, it is farming that bears the brunt of the drought. In developing countries, 83% of the economic losses due to water scarcity were from farms, according to FAO.
As experts have pointed out, relying on the current solution of using groundwater and irrigation to compensate for failing rains makes the drought worse.
It is necessary to find new ways of growing food to sustain current and future populations. Agricultural methods, which are adapted to drought and use less water, are needed since water is one of the most important factors contributing to yield. A comprehensive overhaul is needed and should include the following:
It is easier to reduce water consumption in orchards and vineyards with drip irrigation. This system is, however, not useful in close growing crops like grains. Sprinkler or surface irrigation is necessary for growing grains.
Sprinklers are useful in both farms and orchards. However, this irrigation system can be expensive, and most small farmers, especially in developing countries, cannot afford it.
Therefore, surface irrigation, the oldest form of watering, remains the most common method as it is less expensive and involves less technology, according to FAO.
Even where sprinklers and surface irrigation is used, it is still possible to optimise water use with data-driven Precision Farming. Use of new technology and analysis can minimise the impact of drought on yields and income.
Precision farming relies on data collection of each area of a farm to find differences in conditions of water and nutrient availability. The data is analysed to find out how many inputs to apply. This can prevent overuse and ensure optimum supply. This variable rate application is the core principle of precision farming that can help drought-ridden farms.
There are large scale and small scale methods to assess drought risk to advice irrigation. The methods and tools determine the amount of water in the soil or the growth of plants to find out which areas of the farms need more water, how much of it, and when. Some of the more popular choices are covered below.
The most common method used to collect information on drought for a locality or region is satellite imagery. It is useful for organisations and government departments who advise farmers for future planning.
Satellite imagery taken through remote sensing shows the difference in plants’ health based on spectrometry. Different parts of the visible light range are reflected by the water content and different compounds that make up a plant tissue, so plants with more water will reflect more infrared light. Water can make up to 50 to 90% of a plant. So, spectrometry is an important means of finding out the amount of water in a plant and detecting signs of stress due to drought.
Figure 2: The difference in infrared light reflectance by corn, soybean, and wheat crops. The corresponding relative water content (RWC) in plants is also given. (Image credits: http://cstars.metro.ucdavis.edu/files/3613/4419/0702/Lecture_3-Leaves__Plants.pdf)
Satellite imagery is important in easily detecting the impact of drought in large forests, as well.
Several field based tools can be used to monitor water availability to plants in real time. They are useful for farms, orchards, and forests which want to use precision management. These tools include the following:
Soil sensors- There several models available, and come in varying sizes.
Crop Sensors- These sensors get their data by checking the plant response to their environmental conditions. These are suitable for grain crops, horticulture, and vineyards.
The regions that are most likely to be affected by drought are not necessarily those with more meteorological drought. Instead, it is countries and areas that are ill-prepared to face these challenges due to social, political, and economic conditions that will be hit the worst by drought. For example, drought ridden California farms get only 25% of the normal supplies, but farmers who have used precision farming methods could still sustain their production rates. However, the adoption of variable rate application of inputs is not spreading fast enough. Proper planning and preparation can adapt farms to prevent loss of livelihoods and profits due to drought in developing and developed countries.
Science Writer, CID Bio-Science
Ph.D. Ecology and Environmental Science, B.Sc Agriculture
Feature image courtesy of U.S Department of Agriculture
Carrão, H., Naumann, G., & Barbosa, P. (2016). Mapping global patterns of drought risk: An empirical framework based on sub-national estimates of hazard, exposure, and vulnerability. Global Environmental Change 39, 108-124. https://doi.org/10.1016/j.gloenvcha.2016.04.012
FAO. Chapter 7. Choosing an Irrigation Method. Retrieved from http://www.fao.org/3/S8684E/s8684e08.htm
FAO. ( 2017, June 16). Drought and Agriculture - Predict, Plan, and Prepare: Stop. Retrieved from https://www.youtube.com/watch?v=J5WMyD9-CHs
FAO. (2018). Disasters causing billions in agricultural losses, with drought leading the way. Retrieved from http://www.fao.org/news/story/en/item/1106977/icode/
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Lecture 3-Leaves. Retrieved from http://cstars.metro.ucdavis.edu/files/3613/4419/0702/Lecture_3-Leaves__Plants.pdf
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Tweed, K. (2015, April 25). The Promise of Precision Agriculture in Drought-Ridden, California. Retrieved from https://spectrum.ieee.org/energywise/energy/environment/the-promise-of-precision-agriculture-in-droughtridden-california
UNCCD. (2019). Land and Drought | UNCCD. Retrieved from https://www.unccd.int/issues/land-and-drought
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Union of Concerned Scientists. Causes of Drought: What's the Climate Connection? Retrieved from https://www.ucsusa.org/global-warming/science-and-impacts/impacts/causes-of-drought-climate-change-connection.html