Container gardening on saline soils (Willem VAN COTTHEM)

All over the world people are looking for good solutions when trying to grow plants (trees, vegetables) on saline soils.  It certainly isn’t the easiest thing to do.

This week I received the query below :

Dear Prof. van Cotthem,

My apologies for a completely unexpected mail query, but I feel you are the only desertification/ veg gardening expert who could perhaps help me out.

I’m wondering how to use a strip of beach here in Mumbai (India) for vegetable production: a lot of fibrous coconut material is available on the spot. There are a number of well established shrubs and trees around, but still the soil is pretty sandy and saline. My idea is to introduce Inositol in the equation in some naturally available form, and try out beets or spinach. This land belongs to a charitable trust enabling orphanages from Mumbai to bring there wards there for a holiday. The idea is to grow this vegetables, make them available for the kids, and may be get the kids interested in growing things on seemingly hopeless substrates.

Now that I’ve explained my position, may I hope for some advice from you??

Regards,

Rca Godbole”

——————-

Dear Rca Godbole,

Sincere thanks for this message and your appreciation.  Although I am not an expert on saline soils, I hope to be able to help you with some practical suggestions.

Let me tell you first that I am not aware of any use of Inositol to improve plant growth on saline soils.  I know that research work on salt tolerance in plants showed that :

leaf chiro-inositol level increased dramatically as salinity increased, which can contribute significantly to alleviation of salt stress impact. The enhanced accumulation of chiro-inositol by salt stress appears an important physiological process for L. plants to adapt to salt stress. This work also provides new information for gene target search in transformation via biotechnology for enhanced crop slat tolerance.” (see http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=176716).

I understand that chiro-inositol is produced inside the leaves of some plants growing on saline soils, but that this chemical is not used as a soil amendment.  I will check literature on that.

The same article mentions :

Interpretive Summary: High soil salinity or salt stress is a worldwide environmental factor seriously limiting crop growth and yield. The salt-affected land amounts to more than 900 million hectares. Because irrigating water is rarely salt-free, irrigation adds salts into soil and keeps turning more acreage into saline land. However, about half of the world’s land surface is dryland, which can only be made more productive by irrigation. Furthermore, most crops are salt sensitive but global human population continues to increase and maybe will increase by 50% by 2050. Obviously, salinity is a threat to agricultural productivity. Thus, reducing the impact of salinity and improving crop production through increasing crop salt tolerance are important global goals. Floral crops, they exhibit great diversity in their salt tolerance but little is known on their most growth-related physiological processes in response to salinity.”

I fully agree with the description above.  Reducing the impact of salinity and improving crop production through increasing salt tolerance are indeed important global goals. Unfortunately, science did not yet progress far enough to provide us with salt tolerant varieties of all our food crops.  So, we have to come up, for the time being, with other feasible practices to achieve our primary goal : “to grow these vegetables, make them available for the kids, and maybe get the kids interested in growing things on seemingly hopeless substrates” (like you described it so well).

I am convinced that it will be extremely difficult to improve the soil qualities of that sandy and saline beach in Mumbai (and every other beach) significantly enough to make plant growth on such a hostile substrate possible (except for halophytic or “salt-liking” species).  Most of our food crops are not halophytic.  Therefore, I am not in favour of growing food crops (vegetables, fruit trees etc.) on the beaches.  Nevertheless, I have the pleasure of suggesting you to try it with “container gardening” (see a lot of practical suggestions on this blog).

The basic idea is that any container (pot, plastic bottle, barrel, drum, small or big plastic bags, etc.) can easily be transformed into a substrate on which vegetables and fruiting plants can be grown.  This enormous variety of containers offers us a thousand chances to position these containers on every single open space (even on vertical racks).

Filling up the containers we will use for growing food crops with a non-saline substrate, means automatically that we do not have to take into account the nature of the local soil anymore.  Any container garden can be installed on a concrete soil, e.g. a roof garden, on a barren peace of land in the cities and, thus, also on a beach.  The reason is very simple : the roots are not growing in the local soil anymore, but in the substrate inside the containers.

There is a second extremely positive aspect of container gardening : the quantity of irrigation water needed is significantly smaller than in normal gardening : infiltration of irrigation water in the local soil is limited to a strict minimum, evaporation is only possible at the top of the container (not laterally through the wall of the container, except for clay pots) and, last but not least, if numerous containers are placed close to one another there will be a more humid microclimate created around the growing plants.

Let me ask you to consider the installation of a container garden on that piece of beach you have in view.  Studying the opportunities of involving all the kids in growing their own vegetables in their own containers, you will discover the tremendous advantages of producing food crops “above” the saline sands of the beach, without having to cure the incurable : salinity and drought.

I remain yours for more exchanges of ideas on food production in the most hostile environments.

Let’s do it for the kids !

Willem


Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.