Los capullitos o cascarillas del arroz fue uno de los ingredientes utilizados para cambiar las características de un suelo que inhibía el crecimiento adecuado de cerezos.

How Bio-inputs Change Heavy Soils Used in Rice Cultivation To Grow Fragile Cherry Crops

The boom of cherry exports to China has resulted in the expansion of plantations towards new productive areas. Many important surfaces that were previously dedicated to rice cultivation are now red with cherry trees. However, this process requires overcoming heavy soil conditions with low permeability. It’s a challenge where the use of organic matter and biostimulants is crucial, as is expressed by adviser Jean Paul Joublan, experienced in the Chilean Mantul Estate.

Francisco Fabres

Combining rice with cherries may be an unusual menu, but it’s the recipe chosen by those behind the Chilean Mantul estate. Located in the country’s central area, its 1,200 hectares (ha) have historically been dedicated to rice production. However, 16 years ago it began to dedicate land to produce Stella and Lapins cherry varieties. Positive initial results led to an increase in cherry production, including the Santina, Sweet Heart, Regina, Kordia and Skeena varieties. Their most recent plantation dates to 2020, with adds up to 100 hectares.  

It was a groundbreaking exercise for the country: although cherry fields have been expanding in central Chile because of China's growing demand, Mantul was the first to grow the fruit in the heavy soils that predominate in rice fields. However, they also encountered unprecedented problems: although the new cherry plants had a good initial performance, over time they presented difficulties in important areas. The roots began to suffer because of the accumulation of water in clayey soils and this affected the productive outcome. 

This led the firm to hire the technical consultant Jean Paul Joublan at the beginning of 2021, who faced a difficult fruit scenario. The cherries were so small and had such low commercial value that a great part of the production was not harvested. "From my point of view, it would have been preferable to have half the load, but with a commercial size," he says. 

The source of the problem was in the soil: a surface layer that prevents the infiltration of water when it dries, dehydrating the upper part of the root system. Around 40-50 centimeters underground there is a hard layer, hardpan, that creates a barrier where excess moisture accumulates. While this is convenient for the type of planting and irrigation used in rice crops, in cherry trees this causes roots to dry out at the top and rot below. "It's the worst of all worlds," says the expert.

Agronomist Sergio Videla and consultant Jean Paul Jublan carried out a strategy of organic products to modify the water problems that arise in gredoso soils.

The strategy used to face this challenge has two main facets. The first is to adjust drip irrigation precision to the maximum with the primary aim of avoiding waterlogging of the cherry tree’s roots. The second is soil management, for which a decisive measure has been the incorporation of organic matter and other bio-inputs to prevent compaction in the ridges.

Tranforming the soil

At 30-40 cm, there had been practically no water since spring. That’s where the largest number of roots were found, dehydrated and even dead, non-operative. Therefore, actions were focused on them.

The first step was regulating the problem of the clay that, when dry, tends to become impermeable and hinders water infiltration. Taking advantage of the association with the rice factory Arrocera Mantul, the farm began to use rice husks, which are considered industrial waste. This input is incorporated with a handcrafted tool made from old machine scraps: a kind of claw with two chisel points that penetrates about 20 cm deep and breaks the crust on the ridge to distribute the husk over the plantation row.

"The more, the better," replies Mantul's administrator, Sergio Videla, when asked how much husk should be applied. Even in recent plantations, which are located on loamier soils, this organic matter has been incorporated, since the surface layer there is also clayey.

Another important tool is the application of organic carbon and humic acid. The latter is applied 40 days before the radical spring flashes , after harvest and before dormancy. But Joublan recommends being careful when choosing the product, because, when not adequately formulated, some tend to clog droppers due to the high concentration of humins.

Antes=Befores. Después=After. Although there is no harvest yet, improved biological soil management has had a noticeable impact on the trees in the field, which allows to anticipate better fruit and production.

The advisor proposes using humic acids in a localized form in the irrigation bulb, so that the small volumes that are applied do not dilute their effect in the large volume of soil. The leonardites, he says, are a good option, which can even be applied with plaster, another input aimed at improving the soil structure.

With these products and the organic matter, the clays are separated or flocculated, improving their permeability. “There are many practices that aim for this result. Which one are you going to use? Hopefully all of them,” says Joublan. "These soils are easily compacted, so you have to take short, medium and long-term measures like those indicated above."

The results are already beginning to show. After the application of these biological inputs, the trees have had a remarkable recovery, and the revisions of the intervened soils show that there is no longer a dry sector above nor any excess moisture below. 

Although the first harvest with the new treatment has not yet been carried out, the projections are optimistic not only in terms of kilos per hectare but, especially, regarding the quality and size of the fruit.