Looking for irrigation solution for a big orchard with clay soil and salty spring water

Question

Some facts about the property

• Area: 4 hectares
• Altitude: 1600m from sea level
• Zone 6: Winter lows down to -20 celisius.
• Full sun more than 95% of year
• Yearly Rainfall/Snow 50- 200ml
• Access to a shared spring water 48 hours every 12 days. the water is not salty but has a relatively high Salt + Sulfur content
• soil is Heavy clay
• the previous owners had used the property as an orchard, around 30% of the land has some 5- 15 years old trees of plums, apples, pears and grapes. the rest of the trees have died for various reasons, most importantly suffocation from excess salt build up. some walnut trees also exists but they are still as big as a seedling after 15 years. - there are two big ponds built into the property high up, for water storage of plastic - traditionally the farmers in the area grow almonds, apples, pears, plums, apricots and walnuts. besides many farms are just monoculture wheat, corn, sugar beet and potato. however since each (group of farms rely on a different local spring water and each spring has different mineral profile I can't just copy their style and except the same results. - own it since autumn 2020 and this is the first time I own a land for agriculture

What I'm aiming for

Taking full advantage of the land and its properties and produce as much food and other organic material as possible for income as well as, -Full self sufficient off-grid and organic living using, -Permacuture Food forest (native traditional farming really.. however I want to incorporate the ideas from the modern era permaculture as well, hoping for a better result)

Challenges

Besides harsh weather, the main solution I'm researching right now is the irrigation. The previous owners of the property have tried flood irrigation and dripping irrigation but they all have resigned in frustration as far as I know for the reasons bellow:

• Flood irrigation causes excess salt build up in the soil, besides heavy clay causes soil erosion all the time by the moving water and requires maintenance all the time
• Dripping irrigation breaks quite fast because of the sediment build up in the drippers and rodents destroying the plastic pipes all around
• Minimal water infiltration due to clay soil has resulted in dwarf trees

For water, here are the test results from lab:

• EC: 2080 us/cm
• Salt: 1.56 ppt
• Ca: 168 mg/l
• Na: 230 mg/l
• Sulfates: 116 mg/l
• Mg: 72 mg/l
• K: 4.1 mg/l
• Ba: 1.5 mg/l
• Nitrates (NO3): 2.21 mg/l
• Nitrites (NO2): 0.0049 mg/l

anyone having dealt with the same scenarios who want to share some ideas?

Answer 1

We are told that back in ancient history when the Roman armies wished to punish a village for non-cooperation the commander would issue an order "salt their fields"; This did not work very well in some areas because the soil was reasonably light and normal rains would flush the salt down out of reach of the roots of plants so crops would grow again after they had left. In another parallel situation human urine can be used as a very good nitrogen fertilizer when correctly diluted; however this only works again on lighter soils since urine is quite high in salt which can persist when the soil is heavy. So these are two situations where salt is a problem because of the nature of the soil profile, and yet agriculture/horticulture can continue where the soil is suitable.

This brings us to three solutions: grow plants that are highly salt tolerant, treat the water before irrigation, or change the soil profile.

Soil: normally clay soils are good since they bind very closely with chemicals which is great for fertilizer - you don't have to use much at all. It's also very bad for salt since the salt hangs around for a long time. In a temperate climate (and I rather read into your narrative that you are in a rather more dry Mediterranean profile) the solution to heavy clay is more organic matter thoroughly incorporated into the soil. So first examine the waste products of the area to see if there is a surplus that can be turned to use. Incorporated or as mulch. If no waste in sufficient quantity then consider adding sand to increase the air pores in the soil and speed up the drainage rate.

Treatment: consult with an agricultural chemist to explore storing the irrigation water to get the salts to precipitate out before application to the trees. Run a number of tests on water samples to see if solution works. Nothing further to say on that.

Drought tolerant so skip the irrigation: the olive is of course the traditional tree for dry areas. Also prickly pear, agave, grape (you mention this so you are the expert there), pineapple, sapote. The apples, pears, and so on are a bunch of fluff that no doubt command higher prices in the market but will cause a farmer to lose sleep and break his back for nothing.

One final thought - asparagus?