What Dr. Luke has to Say About Relieving Drought Stress Brought by Crop Management - Part I


Managing Drought Stress by Supplemental Irrigation



Xiang Qing Kong had just finished reading an article in the local newspaper about irrigation.  He was 47 years old and a farmer.  He and many of his friends who were farmers were very interested in developing an irrigation system.  There were two problems.  One was the cost; the second was how to do it.  They did have some small irrigation systems but they felt that in general they were not as good as they needed.  They contacted the local agricultural expert and arranged a meeting with them.  The agricultural expert came and gave them a lecture on managing drought stress by supplemental irrigation.  He did this as Xiang Qing Kong's area of China had mild drought conditions for several years.

The agricultural expert started by saying, irrigation, where available, is the major means for combating drought conditions. It is a prime approach to the intensification of agriculture and the generation of stable income. The development of irrigation depends on various environmental, economical and social factors.  However, there are hazards in irrigation if practiced indiscriminately, such as soil erosion, soil salination, soil leaching and soil disease infection.

The key to planning an irrigation system and scheduling is knowledge of the crop, the soil properties and the potential evapotranspiration of the specific crop at the site. This information can also be used to estimate dryland crop water use and deficit at any given time during the crop cycle.

Supplemental irrigation is the most common irrigation practice for crops not designated for fully irrigated conditions. Supplementary irrigation is a practice dictated by constraints, which can be derived from the limited availability of water, irrigation equipment, the cost of water, or other economical and technical constraints. With

Supplemental irrigation the amount of water applied to the crop in irrigation is well below the full requirement of the crop.

Modern dryland farming is a system of low inputs combined with soil and water conservation practices and risk reducing strategies. The system can be sustainable if practiced properly.  Water shortage is the main limiting factor, but successful dryland systems also maintain reasonable practices to eliminate other limiting factors (poor nutrient status, weeds, biotic stresses, etc'), which can reduce the efficiency by which the crop uses the limited moisture.

The most advanced systems have been developed in the Great Plains of the USA and Southern Australia, even though traditional systems employed in Asia and the Middle East also offer important insights. In the USA, the lesson learned during the "dustbowl" years in the early 1900's prompted extensive development in dryland farming systems. These systems and the associated technological progress such as plant breeding, brought about an increase in mean winter wheat yield from 0.5 ton ha-2 in 1930 to about 2 ton ha-2 in 1980. In Southern Australia the "ley farming" system was developed in the 1920's and adopted widely in the late 1940's. The system involves a rotation between a self-seeding legume grown for several years and wheat. The farmer grows wheat and raises sheep while the legume serves to sustain soil fertility (mainly nitrogen).

 The lesson learned from the American and Australian experience is that the development of a sustainable dryland farming system involve the following principles, not necessarily in their order of importance:

  1. Conservation Tillage
  2. Weed Control
  3. Soil Fertility Management
  4. Diversified Farming
  5. Species Selection/Variety

Xiang Qing Kong was very interested in irrigation after this lecture.  He was interested to know more about these five points and how to use them in farming and irrigation.  However, the agricultural expert had concluded for now and said latter in the day he would finish the lecture.  Xiang Qing Kong began to discuss the lecture with several of his friends.  He and his friends knew that they probably needed to have more irrigation, however, knowing how they could do this as well knowing the cost of irrigation was important.  Xiang Qing Kong told his friend's that nothing could be worse than a drought destroying your farm.  He knew that if they had one or two years where they had no rain then drought could destroy his and many of his friend's farms.  What would they do if this happened?

One of Xiang Qing Kong's friends told him that there was something worse than loosing your farm due to drought.  That was having an unhappy life now even with a farm as well as after death to not know what will happen to you.  Xiang Qing Kong knew that Chinese did not like talk to about what happens after death.  However Xiang Qing Kong was very interested in what could be more important than drought, irrigation and having a farm.  His friend told him that there was a way to know that you could have a happy life now and for all eternity.

Xiang Qing Kong's friend turned to a place in the Bible written by a follower of Jesus about 90AD.  Jesus himself said these words. It said, 'if anyone is thirsty, let him come to me and drink.  Whoever believes in me, as the Scripture (or Bible) has said, streams of living water will flow from within him (John 7.37,38).'  Xiang Qing Kong did not know what was meant by 'believe in me' and 'streams of living water will flow from Jesus.'  His friend said that the statement 'streams of living water' meant that God would literally live in us and give us a joyful life now and eternal life.  If we believed this then we would have 'these streams of living water' in our lives.  Jesus was speaking figuratively and not literally.

Xiang Qing Kong's friend showed him another place in the Bible.  This place said, 'as the deer pants for the streams of water, so my soul pants for you, O God.  My soul thirsts for God, for the living God.  When can I go and meet with God? (Psalms 42.1,2).'  Xiang Qing Kong's friend asked him if he thirsted for God like his plants thirsted for irrigation?  Frankly no, said Xiang Qing Kong.  He said that he really did not think a lot about God. Xiang Qing Kong's friend told him that the Bible told why he did not thirst for God. Xiang Qing Kong was very interested to know why he was like this.  He thought it was interesting to know why he acted a certain way and thought a certain way.  How could the Bible know this about him?

Before they were able to finish this discussion the agricultural expert returned.  They were to continue the lecture on irrigation in drought type circumstances.  The expert said he would start talking about the five points mentioned in the last lecture for the development of a sustainable dryland farming system.  What they could not finish now they could finish at another time.  The expert said he would start with conservation tillage.

With conservation tillage the fallow system is designed to conserve soil moisture from one season to another or from one year to the other, depending on climate and crop. Increasing storage of soil moisture by the fallow system with or without conservation tillage is standard agricultural practice in dryland farming. The benefit of fallow and conservation tillage in terms of increasing available soil moisture to the crop depends on soil water-holding capacity, climate, topography and management practices. Fallow efficiency, in terms of percent increase in soil moisture availability to the crop measured at planting date normally ranges from about 5% to 30%. While these amounts are not impressive they can make a difference between crop failure and success. The fallow carries additional benefits such as improved soil nutrients availability and the eradication of certain soil-born pests, such as nematodes.

Conservation tillage involves the principle of minimized tillage operations to conserve soil structure and to maintain ground cover by mulch, such as stubble. These practices reduce water runoff and increase soil infiltration. Conservation tillage has become the cornerstone of dryland systems in certain regions of the USA, Canada and other regions. While the benefits of conservation tillage are well documented it has also been noted that crop residues under this system may promote certain crop diseases.  In certain soils deep tillage was found very useful to improve soil moisture storage, especially when hard soils or hardpans are a problem.

The next point for developing a sustainable dryland farming system is weed control.  Controlling weed pressure is important during all kinds of weather patterns, but it is even more important during times of drought.  Weeds generally have deeper roots and can remove more water than the crop, which just adds to the drought conditions.  Controlling weeds can be especially difficult during times of drought.  This is for two reasons.  First of all, during drought conditions the hardier weeds are more prevalent.  These weeds are harder to control and are more competitive with the planted crop.  Secondly, many herbicides for controlling weeds only work when plants are actively growing.  Many times during drought conditions it is hard to find a time when the weeds are actively growing.

This lecture was concluded for the day.  Xiang Qing Kong though was very glad to have learned so much useful information regarding irrigation in drought conditions.  He was hopeful he could continue to learn about this and put this into practice. It was late and the bus ride back home was long so Xiang Qing Kong and his friend decided to stop into a restaurant and have some noodles. 

While in the restaurant they continued the discussion about how the Bible could know Xiang Qing Kong's thoughts towards God.  His friend turned to a place in the Bible which stated, 'Therefore everyone who hears these words of mine and puts them into practice is like a wise man who built his house on the rock.  The rain came down, the streams rose, and the winds blew and beat against that house; yet it did not fall, because it had its foundation on the rock.  But everyone who hears these words of mine and does not put them into practice is like a foolish man who built his house on sand.  The rain came down, the streams rose, and the winds blew and beat against that house, and it fell with a great crash (Matthew 7.24-27).'  Xiang Qing Kong's friend told him a wise man is determined by who listens and puts the Word of God, which is the Bible, into practice.  Those who do are saved from the storm; those who do not are destroyed by the storm.  Xiang Qing Kong knew in storms how quickly rivers can swell up and destroy areas not secure, especially buildings.

Next Xiang Qing Kong's friend showed him the passage, which showed him why he did not follow God.  This was written about 700BC and was included in the Bible.  This passage states, 'Surely he took up our infirmities and carried our sorrows, yet we considered him stricken by God, smitten by him, and afflicted.  But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was upon him, and by his wounds we are healed.  We all, like sheep, have gone astray, each of us has turned to his own way; and the Lord has laid on him the iniquity of us all (Isaiah 53.4-6).'

Xiang Qing Kong's friend said that all of us towards God have, like sheep, gone our own ways.  Both of them had seen sheep and knew how they could act.  Sheep didn't listen very well.  That, Xiang Qing Kong's friend said was what humans did toward God, that is they went their own way.  They ignored God.  That, Xiang Qing Kong's friend said is what all people have done.  He showed him another place, in the Bible, which said, 'for all have sinned and fallen short of the glory of God (Romans 3.23).'  Everyone who has every lived has gone against what God wants for us.  The result was death, death towards being able to turn to God now and eternal death after we die.  Another place in the Bible said, 'for the wages of sin is death but the gift of God is eternal life through Jesus Christ (Romans 6.23).'  Our wages for our sin or indifference or being like sheep and going away from God is death, but God gave us eternal life through Jesus Christ. 

Xiang Qing Kong wanted to know how he could know God so he could have those springs of living water flowing through him?  His friend returned to that prior passage which said, Jesus Christ carried our sorrows and infirmities and took our punishment.  This meant that though we did wrong, Jesus Christ took our punishment so we could have a right relationship with God. 

Xiang Qing Kong's friend went to another place in the Bible, which said, 'if you confess with your mouth the Lord Jesus and believe in your heart that God raised him from the dead you will be saved (Romans 10.9).'  This meant if you confess that Jesus is Lord of your life because he took your sins on the Cross and then believe that after he did this he rose from the grave to prove his power over sin and death you will be saved.  This salvation will save you from your sins both now and for all eternity and give you new life now and also for all eternity. 

Xiang Qing Kong wanted to have this new life in Jesus Christ.  He and his friend prayed the following prayer together.  'Dear Lord, I know that I have sinned against you. I believe that you died on the Cross-to take away my sin so that I would not have to bear the punishment for those sins.  I believe that after you died you rose from the dead to show that you have victory over sin and death and that you are alive today.  I ask you to come into my heart to give me a new life now and eternal life.'  Xiang Qing Kong prayed this prayer and gained new life both now and forevermore.   He also learned how God can not only quench his thirst for eternal life but how God is also in control of the rains which quench the thirst of thirsty plants.  You too can pray this prayer and gain eternal life.