Why can water-saving and drought-resistant rice in Africa save 40% water and reduce methane emissions by 70%?

Key takeaways:

• 1

  As the main food crop on which human beings depend, rice feeds more than half of the world's population and is the main food in developing countries.

• 2

  The promotion of ultra-high-yielding varieties requires a large amount of irrigation and fertilizer inputs, which increases the cost of rice production and has an impact on the environment, most notably non-point source pollution.

• 3

  Compared with ordinary rice, water-saving and drought-resistant rice has advantages in water use, fertilizer utilization, planting methods, and carbon emissions.

• 4

  Water-saving and drought-resistant rice is a very promising type of rice variety that can help solve food security problems and also respond to climate change and reduce the risk of future climate change.

In the face of a rapidly changing global climate, food security has received widespread attention. At COP28, 134 countries signed the UAE Declaration on Resilient Food Systems, Sustainable Agriculture and Climate Action to support food security while tackling climate change.

Among them, rice, which provides a food source for nearly 50% of the world's population, is one of the most important food crops on the continent and even in the world, and the crisis it faces in the context of climate change cannot be ignored.

Addressing climate change mainly involves two aspects, one is mitigation and the other is adaptation. Mr. Liu and his team have been committed to the development and promotion of water-saving and drought-resistant rice to meet the challenges of climate change.

Narrator: Liu Zaochang丨Researcher, Shanghai Agricultural Gene Center

1. The history of rice variety innovation in the millennium: increasing yield is the key

1. How to renew rice?

As the main food crop on which human beings depend, rice feeds more than half of the world's population and is the main food in developing countries, especially in poor and backward countries.

The origin center of rice is located in the border areas of China, Myanmar, India and other regions, and the first to evolve from wild rice was the indica rice subspecies, and later people produced in high-latitude or low-latitude high-altitude mountainous areas, and indica rice further evolved into a short-grained japonica rice subspecies.

90% of the world's rice production areas are in Northeast Asia, East Asia, Southeast Asia, or South Asia. Over the years, Africa's economy has gradually developed, and dietary Xi and food consumption structure have changed, which is reflected in the gradual increase in rice consumption and the expansion of rice cultivation areas on the African continent.

Cultivated rice is divided into two cultivated varieties: Asian cultivated rice and African cultivated rice. The share of African cultivated rice in commercial rice varieties is very small and almost negligible. There are many cultivated rice producing areas in Asia, and the rice in other rice producing areas is basically from Asian cultivated rice varieties, and the amount of cultivated rice from Africa is very small. There are two subspecies of cultivated rice in Asia, indica and japonica, which further differentiate into rice and upland rice varieties or ecotypes.

Rice is found in swampy low-lying areas, and is now the main rice-producing areas in Southeast Asia. Upland rice is distributed in the inter-mountainous dryland hills of Southeast Asia, including terraced fields, and has very good adaptability and drought tolerance, but the yield is low, and the quality of rice is relatively poor.

Over the past 70 years, rice varieties have undergone great changes, especially in the emergence of four distinct variety development stages.

In the 1950s, it was the tall rice variety, with the development of the rice green revolution, the dwarf variety appeared and replaced the tall stalk variety in the 60s, the hybrid rice variety appeared in the 80s, and the concept of super rice variety was proposed after 1990.

From tall stalks to dwarf stalks, to hybrid rice, and super rice, with each change of variety, the yield level of rice has increased significantly. The material consumption in the modern rice industry, especially the consumption of water resources and fertilizers, is relatively high, but the fertilizer utilization effect is still very low.

2. The dilemma faced by variety innovation

There are two characteristics in the rice variety innovation process: a high degree of mechanization and a high level of chemical input.

The input of various herbicides and pesticides has increased the cost of rice production and affected the environment, the most significant of which is the problem of non-point source pollution.

The promotion of ultra-high-yielding varieties requires large irrigation and fertilizer inputs. If there is less fertilization, the rice cannot grow, and it is difficult to reflect the high yield performance of this variety. However, the use efficiency of nitrogen, phosphorus and potassium, the three elements of fertilizer, is relatively low, and two-thirds of the nutrients cannot be used on average.

In good cases, these nutrients are retained in the soil, but in bad cases, they are lost to the environment through rainfall or soil infiltration, which is the eutrophication of the surrounding water bodies due to excessive fertilization and low utilization. The emission of nitrogen and phosphorus leads to the overflow of cyanobacteria and the decline of water quality, which is a pollution phenomenon that is easily caused in agricultural production, the so-called non-point source pollution.

There is also the issue of greenhouse gas emissions, particularly methane. The organic matter in the soil is returned to the field along with straw and straw, and methane is produced and emitted into the atmosphere under high temperature and anaerobic conditions. Methane produces a greenhouse effect that is more than 25 times higher than that of carbon dioxide. The IPCC 1996 report said that methane emissions from rice paddies account for between 5-20% of methane emissions from human activities, and vary from place to place due to climate and other factors.

At the same time, due to climate change, the rice production process often suffers from drought and water shortage, such as the sowing period, tillering stage, and maturity stage, if it encounters drought, it will reduce the yield of rice.

In the face of such problems, it is indeed a challenge to produce enough food to increase food production and meet growing social needs, and on the other hand, to combat climate change and protect the environment so that rice production can develop in the long term, effectively and sustainably.

In 2003, researcher Luo Lijun, the chief scientist of our center, led a team to start cultivating water-saving and drought-resistant rice. To put it simply, water-saving and drought-resistant rice is an intermediate type of rice and upland rice, with rice on the left and upland rice on the right, which is produced on dry land on the hillside and relies on rainfall to meet water needs.

Rice sowing during the mango planting season (Source: Visual China)

2. Water-saving and drought-resistant rice that exploits its strengths and avoids its weaknesses: lower carbon and wider distribution

1. Where is the quality of water-saving and drought-resistant rice?

In the state of moist soil, the yield of water-saving and drought-resistant rice was comparable to that of ordinary hybrid rice. In addition, due to its drought tolerance, it can be planted in dry land or in dry land with slightly undulating and uneven soil.

The characteristics of drought tolerance make this quality have a wide range of adaptability, this type of rice variety in the cultivation process is not so tolerant to nutrients, especially fertilizer, it does not need so many nutrients, nitrogen fertilizer, urea and other chemical fertilizer amount is only 2/3 of the level of ordinary rice, that is, nearly 3 percent of fertilizer saving.

Since the popularization of hybrid rice in the 80s of the last century, the yield has not increased significantly for a long time, and it has basically stagnated. However, super rice is actually the result of a high-yield competition, and it is difficult to achieve the goal of ultra-high yield in a climate with insufficient rainfall.

Green Super Rice was a concept that was cultivated and proposed by Professor Li Zhikang of the Chinese Academy of Agricultural Sciences and Academician Zhang Qiqi of Central China Agricultural University, together with our team and other parties. It is comparable to the yield level of super rice, but reduces the demand and dependence on water, reduces the amount of chemical fertilizers, improves the use efficiency of water and fertilizer, and at the same time increases the use efficiency of disease and insects, and the use efficiency of nitrogen and phosphorus.

At present, the promotion of water-saving and drought-resistant rice in China is relatively successful, and the annual planting area is almost 200 to 3 million mu. Through nearly 20 years of breeding efforts, the water-saving and drought-resistant rice currently cultivated are indica and japonica water-saving and drought-resistant rice. There are also conventional varieties and hybrid varieties, and there are also conventional varieties and hybrid varieties of japonica rice-type water-saving and drought-resistant rice, which provide convenience for planting and achieve the goal of higher yield.

In summary, compared with the cultivation characteristics of ordinary rice, water-saving and drought-resistant rice can be considered from four aspects.

1. Water utilization. Planting water-saving and drought-resistant rice does not require frequent additional irrigation even if there is no water in the field, as long as the soil is kept moist. Conventional rice production accounts for 70% of the total agricultural water use, agricultural water accounts for 70% of the total water use, and rice production consumes nearly 50% of the national economic water use. Through our demonstration and research results, water-saving and drought-resistant rice can achieve water saving of more than 40% and reduce methane emissions by more than 70%. If the excess nutrients in the soil are not absorbed by the rice in the current season, they will not be easily discharged into the surrounding water bodies, reducing non-point source pollution.

2. Fertilizer use efficiency. Water-saving and drought-resistant rice is currently not very sensitive to fertilizers, and the amount of fertilizer applied is about 30% less than that of ordinary rice, which is comparable to the level of nitrogen fertilizer or other chemical fertilizers used in rice production in Japan.

3. Flexible planting methods. In addition to transplanting, it can be planted in a live broadcast method that saves labor, effort and cost.

Fourth, low carbon emissions. It can not only cope with the climatic conditions that are not conducive to agricultural production such as irregular rainfall or reduced rainfall brought about by climate change, but also in the production process, the cultivation of this variety has greatly reduced the greenhouse gas emissions in the field, especially methane, and has an important contribution to emission reduction, while other emissions such as carbon dioxide and nitrous oxide are equivalent to the level of ordinary rice.

In addition, I believe that everyone is also very concerned about the taste of rice. Traditionally, upland rice has a bad taste, and the rice is harder, more scattered, and has no chewiness. These problems can be solved when taste is improved as a breeding goal.

For example, WDR 73, a water-saving and drought-resistant rice variety, has a better taste than most rice on the market after the drought tolerance gene is introduced into the rice through hybridization, with a certain viscosity and more amylopectin, and the rice is softer. For most rice consumers, they prefer rice that is a little chewy, a little sticky, and will not rot after being boiled for a long time.

Dry excellent 73 meters sample

We aim to improve it in the breeding process, and if we don't, it may not taste good. Africa's rice diet Xi different habits, they mainly make fried rice, and eating hard rice is more in line with their dietary Xi, but we can't eat it at all, and the quality of rice still depends on breeding goals.

2. Where is water-saving and drought-resistant rice distributed?

At present, water-saving and drought-resistant rice has spread to the three main geographical regions of rice production, the rice producing areas in East China and Central China, including the middle and lower reaches of the Yangtze River and the Huaihe River Basin, the southwest rice region and the northern rice region. The planting areas of japonica rice, including Xinjiang, have also begun to demonstrate the cultivation of water-saving and drought-resistant rice of the japonica rice type.

In summary, the normal rice planting area can be carried out paddy field direct seeding water-saving and drought-resistant rice, after 20 days after the seedling, the seedling group has risen, and some places may grow more sparsely, but through fertilization management and later group self-regulation, higher yield can be achieved.

The Huaihe River Basin in Anhui Province can carry out drought direct seeding, and after the wheat is harvested, water-saving and drought-resistant rice can be replanted, and wheat rice can be planted twice a year and multi-cropping, so as to increase grain production, and there are both summer and autumn grains. This is a typical way to grow water-saving and drought-resistant rice by using dry direct seeding in the rice area of Northeast China.

Another important application scenario is the conversion of mountains to fields in the south. In some places in the south, the proportion of cultivated land is very low, especially with the economic development and the increase of industrial construction land, it is hoped that the hillside land and low hills can be transformed into terraced cultivated land, which is more common in Zhejiang, Hunan, Guangxi, etc. Like the standard terraces cultivated in Yiwu, Jinhua and other places in Zhejiang, the cost of transformation is also relatively high, the cost of 1 mu is more than 100,000 yuan, or even 200,000 yuan, in the economically developed places, such practice can indeed be carried out. Although the short-term investment is high, it is feasible in the long run, and the preferred pioneer crop for such mountain conversion is water-saving and drought-resistant rice. Direct seeding planting on sloping land, the yield is also very good, basically up to 400 kg per mu, and 600 kg if it is good. The picture shows the widespread application of water-saving and drought-resistant rice in newly renovated fields. This is the application of water-saving and drought-resistant rice in mountainous areas with steep slopes, such as Guizhou, where the slopes are very steep as you can see from the photos.

3. China's Rice Enters Africa: Helping Africa Achieve Food Self-Sufficiency

1. Why did water-saving and drought-resistant rice enter Africa?

In order to implement the "Belt and Road", we have also brought water-saving and drought-resistant rice to Africa. Most places in Africa are above 1,000 meters above sea level, and we have also carried out simulated cultivation trials at high altitudes, and the planting situation in Guizhou is that there are unique climatic and soil conditions, and the yield will increase.

Agricultural development is an important part of the country's "One Belt, One Road" initiative, and since the 70s of the last century, various localities have carried out aid to Africa. In the past, aid to Africa was mainly "blood transfusion" to promote Chinese rice to Africa. From the 70s to the present, China-Africa agricultural cooperation has paid more and more attention to the investment of agricultural high-tech, such as the construction of agricultural demonstration zones, including planting and aquaculture.

The construction of agricultural demonstration zones simply means allocating a certain amount of land, such as the construction of a demonstration park with an area of 100 acres or the construction of institutions of a similar nature as the Agricultural Research Institute. However, in the process of practice, the construction role of the demonstration area is still limited, and for African countries, they are more likely to feel the direct impact of industrial projects, infrastructure construction and other projects, but for the majority of farmers, they cannot feel the role of the demonstration area to them. In 2016, along with the scientific and technological activities of Chinese enterprises in Africa, we began to explore and recommend the promotion of water-saving and drought-resistant rice, and wanted to see if water-saving and drought-resistant rice could help solve Africa's food problems.

The primary feature of Africa's food production and supply is its basic dependence on imports. Although rice consumption in Africa is increasing, there is no rice production in many places, for example, Botswana, South Africa, is increasing rice consumption, but it is all imported from Southeast Asia and the Americas, which puts a burden on the economy. Many developing countries are worried about their own food security, and if international supplies are affected or cut off, food imports will be affected.

In the face of these challenges, many small African countries have also proposed food self-sufficiency, hoping to use their own land resources to produce food.

The second characteristic is that there are few paddy fields, but the reserve arable land resources are very abundant. Although many people have the impression that the land of Africa is a very arid and hot place, this is actually mainly in the region of North Africa, and there are still large areas of very good land resources in the Middle East and Africa, with a certain slope, abundant sunshine and rain, and great potential for food production.

Faced with these situations, one possible solution is to learn from Xi experience of rice cultivation in Asia and develop high-yield rice fields. However, the cost input is very high, and the cost of mountain to field conversion in Zhejiang is 100,000-200,000 yuan/mu. In Africa, even if the cost is halved, it is currently a very large economic burden for African countries, and the income is relatively slow.

The second is to expand the grain planting area in the short term, and to grow rice under the condition of natural rainfall under the condition of uneven fields, which is a more practical and feasible way, but the problem of this solution is the lack of excellent varieties suitable for such conditions.

Kenya is relatively good at rice cultivation, and European and Indian colonial traders brought Asian rice over and developed some paddy fields, but the area is very small, now only 20,000 hectares. In order to meet the goal of food production and achieve food self-sufficiency in the future, it is necessary to expand the rice cultivation area to 1 million to 2 million hectares.

If such a large area is to be expanded, the best way is to plant it under rain-fed conditions, and to grow rice on dry land where there are currently natural slopes. Places such as Kenya and the Middle East and Africa have joined the Convention on the Conservation of Wetlands, and low-lying areas should also maintain wetlands, and mosquitoes are planted in floods.

2. How can the Chinese experience take root in Africa?

The picture below is our farm for water-saving and drought-resistant rice in Lureo, Uganda. One of the characteristics of this rice farm is that the soil is very good, the land is relatively flat, but the soil aluminum is particularly poisonous, and the poisoning effect is stronger in the case of flooding, resulting in the rice production process in the seedling planting after not tillering, will sit on the sitting.

In this case, it is best to let the water around it drain away, so in the state of dry farming, it can solve the health problems of the rice and make the yield have a greater increase. Since 2019, the farm has been planting water-saving and drought-resistant rice, both seedling raising and direct seeding, with a lot of rice output every year, and can be planted for 2 seasons a year. In addition to the reedy farm, there is also a large area of cultivation on the shores of Lake Victoria, the largest freshwater lake in Africa.

Here I share the story of a small farmer planting water-saving and drought-resistant rice, Dalili, a farmer in the Arua region of northern Uganda, has planted 10 acres of water-saving and drought-resistant rice since 2019, and now the overall investment is very small, I take out the fertilizer amount separately, the amount of nitrogen, phosphorus and potassium fertilizer is only more than 1 kilogram per mu, which is about 1/10 of the level of China's rice field fertilizer, but the yield can reach more than 300 kilograms, and the planting area has been expanded to 60 acres.

Elsewhere in Africa, like Botswana, the climate is drier and the growing season is shorter. The growing season in the southern hemisphere is generally from November to April, but after two years of hard work, it has been successfully planted.

Caption: In cooperation with Africa, the green dots represent nearly a dozen countries that have been planted

Overall, water-saving and drought-resistant rice is a very promising type of rice variety that will contribute to Africa's food self-sufficiency under current conditions. In addition, water-saving and drought-resistant rice can also cope with climate change, which means that it can not only adapt to the changing climate, but also reduce the risk of future climate change through the reduction of soil emissions in the field.

(The above is compiled from the sharing of the Gates Foundation's Global Health and Development Media Workshop)

Organizer: Wang Jiaxin