Almost half of Israel’s agricultural land is at risk of soil erosion, according to estimates by the agriculture ministry division responsible for soil conservation, leading experts to look for radical new ways to tackle a growing concern.
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Farmers across Israel have been experiencing increased soil erosion for many years. Every time short but intense rains pound their lands, they worry that some of their fields have vanished due to soil being washed away with the rushing waters. Undertaking operations to prevent such damage has been a major challenge for the Agriculture and Rural Development Ministry. It’s a known phenomenon in many countries, and the United Nations even declared 2015 as the International Year of Soils in order to raise awareness of the danger.
Erosion occurs during exposure to water or wind. This phenomenon has always been present in nature and in tilled lands. In recent years, though, it has been aggravated due to intensive cultivation of widespread areas, which includes usage of heavy equipment that destabilizes the ground.
Climate change is apparently another factor, bringing with it more frequent extreme downpours with short spans of heavy water flow. For example, the Ashkelon area – which has numerous cultivated areas – experienced 67 millimeters (2.6 inches) of rain within half an hour last November.
According to estimates made by the ministry’s Soil Conservation and Drainage Department, almost half of Israel’s agricultural land is now at risk of erosion. Earlier estimates by the department pointed to 15 percent of the land as having undergone damage and thinning out between 1980 and 2003.
The ability to recover is extremely slow. Whereas 10 centimeters of soil can be lost within hours, natural processes of restoring this amount of soil can take almost 2,000 years. Damage to crops in such cases can amount to a 30 percent yield loss. Damage to the topsoil can affect food production, but other benefits are also impaired – such as the regulation of the flow of floodwaters, the diversity of flora and fauna, and the potential for leisure and recreational activities.
Several surveys in recent years have exposed the extent of the phenomenon. In the Sirin Plateau area northwest of Beit She’an, arable soil with a depth of 100 centimeters was measured 65 years ago. Fifty years later, however, this has shrunk by a quarter. “Our areas are on the slopes of Givat Hamoreh, and we had years in which a tractor could be covered in soil that swept down the hill,” says Eitan Avivi, the manager of field crops at Kibbutz Ein Harod.
“Erosion causes a host of other problems,” notes Eran Ettinger, deputy director general for infrastructure, planning and resource management at the agriculture ministry. “Eroded soil blocks creeks and drainage outlets, as well as spreading pesticide and fertilizer breakdown products.”
A study conducted at the Poleg Stream outlet near Netanya found remains of 20 different pesticides. “When soil is washed away, only God and the sea can stop it,” says Zeev Rahman, the manager of field crops at the Shikma agricultural company.
“We can observe cumulative damage to the best agricultural soils in the country,” says Nissim Almon, the director of the Sharon Drainage and Stream Authority. “Sometimes it’s caused by sudden events and sometimes it’s a drawn-out process. The Poleg area alone suffered damage worth 25 million shekels ($6.6 million) in 2009. We’re struggling to fix this with no state assistance,” added Almon.
It’s not just water or heavy equipment that cause soil instability. Last week, the journal Soil & Tillage Research published a study conducted by researchers from Haifa and Ben-Gurion universities, where they looked at wind erosion of soil in the Negev in relation to different styles of cultivation. The researchers found more erosion in areas where heavy equipment was used or in areas where there was grazing by sheep and goats, in relation to areas in which these were absent. The study suggested that soil fertility will be compromised in the long term due to a reduction in mineral content and other important nutrients such as potassium and phosphates.
The state has changed its approach in recent years, according to officials at the ministry, with increased understanding of the severity of the problems associated with a loss of arable land. Ministry professionals are advising farmers on prevention methods, which include cultivation that enhances soil stability.
Over the last three years, the state has helped by investing 9 million shekels in the purchase of equipment that can perform sowing without a preliminary tilling of the topsoil. There are currently some 300,000 dunams (about 75,000 acres) that are being cultivated with these machines.
Another method involves filling the area between rows of crops with other vegetation. This reduces the amount of friction between raindrops and soil. According to Dr. Jenia Gutman, from the Soil Conservation and Drainage Department at the Society of Ecology and Environmental Sciences, such experiments have been underway for four years in the Sharon region. Using extra vegetation attracts insects that counter other pests, thus reducing the need for pesticides.
Another method involves covering the area with compost, which helps stabilize the soil. In other areas, less ploughing is carried out. In combination, these methods have significantly reduced erosion intensity in agricultural areas between Beit She’an and Afula, in which the problem was particularly acute.
“In recent years we’ve undertaken several measures to reduce erosion. We’ve dug channels to drain the water, with a pipe that regulates the flow,” says Avivi. “Some areas are left uncultivated for part of the time to conserve soil stability. We’ve developed a machine that can plough in a manner that reduces the breakup of soil particles. We’re planning and investing money in different facilities and their maintenance,” added Avivi.
Rahman says farmers have stopped cultivating some areas that depend on rainfall, in order to conserve soil stability. This applies to areas in which the thickness of the most fertile soil is only 30 centimeters. “We sow without ploughing, encouraging growth of other plants so that their roots strengthen the soil. We’ve learned that ploughing causes damage, bringing to the top a nutrient-poor layer while pushing the richer soil under. Our new approach is working well and preventing erosion.”
Soil conservation can blend in with the rehabilitation of ecological systems, mainly in streams – which are vital means of regulating the flow of floodwaters after heavy rains. In the past, drainage authorities used to control the flow in natural streams by digging straight channels that could carry large quantities of water rapidly.
“This accelerated the water flow to these streams, in contrast to the natural course of flow in which water passed through ecological niches along the stream beds,” says Danny Laske, senior coordinator at the Soil Conservation and Drainage Authority. “We now realize that we must change our approach and treat the whole drainage area as one unit.” They are trying to convince farmers to relinquish the edges of their plots in order to broaden streams in the area. There are also attempts to recreate natural stream meanderings in order to regulate the intensity of flow.