Yu. Dzhumaniyazova, N. Ibragimov, Zh. Ruzimov, Zh. Khaitboeva, I. Kuryazov
Non-governmental non-profit association KRASS

Relevance of the invention

The issue of food security arises again and again in our country. Our agricultural yields must be increased in order to produce more food. But this demand comes against a backdrop of the decreasing fertility of our soil. In other words, farmers must produce more while also taking into account the objective facts of production: soil quality, the amount of water, etc. In this article, we will attempt to elucidate how nitrogen is used in agriculture, its influence on harvest yields, and, most importantly, how to regulate the use of nitrogen most effectively in order to get the largest possible harvests.

Every farmer knows that one of the leading measures among the range of agro-technical measures intended to increase the harvest of cotton plants, winter wheat, corn and other crops, is the use of mineral fertilizers, particularly nitrogen fertilizers. Nitrogen plays an important role in nourishing agricultural crops that grow in arid zones. Depending on soil-related, climatic and agro-technical factors, nitrogen fertilizers often deliver an increase in harvest yield of over 50%. Therefore, every farmer makes active use of nitrogen fertilizers in order to give his plants nourishment to grow. However, each plant can only take in as much nitrogen as it needs. Thus the question arises: how can an individual farmer know how much nitrogen each plant requires at each particular moment?

This question is important for several reasons. First of all, nitrogen fertilizer costs money. If a farmer uses nitrogen fertilizer incorrectly, the plant will take as much as it requires but the rest will dissipate into the atmosphere or be washed away. According to calculations carried out by the non-governmental non-profit organization KRASS, no less than 36 million US dollars of incorrectly-used fertilizer evaporates each year from the fields of Uzbekistan. Let us give a simple example. Farmers often apply fertilizer during watering. This leads to more than 40% of the fertilizer being immediately washed away without reaching the plants.

Secondly, if a farmer incorrectly employs nitrogen fertilizer, he/she might not use enough which in turn has affects the harvest. However, plants’ growth is also delayed if there is a surfeit of nitrogen: they grow an extremely large amount of foliage and crops and flax produce fewer seeds, tubers and roots. An excess of nitrogen can also cause lodging. Nitrates (salts of nitrogen and oxygen) easily move around in the soil and can be washed away from the root layer by precipitation and drainage. The washing away of nitrates from heavy soils underneath plants is usually negligeable, on average amounting to 3-5 kg per hectare. However, light and especially fallow soils in damp regions, as well as irrigated land, can lead to significant losses of in excess of 30-50 kg per hectare.

Thirdly, nitrogen is an extremely volatile substance and easily forms bonds with oxygen. Nitrogen joined together with oxygen becomes a greenhouse gas, which has exceptionally harmful effects on worldwide climate change. The effect of nitrous oxide on the climate is more than 298 times greater than the effect of carbon dioxide.
These are some reasons why the correct use of nitrogen fertilizers is important for every farmer as well as for the country as a whole and the entire world’s population.
The current guideline amounts and time periods for applying nitrogen fertilizer are very general and rarely take into account the particular characteristics of soils and agricultural crops or prevailing climatic conditions. The amount of mineral nitrogen contained in soil can vary enormously depending on many soil-related and ecological factors. This makes it difficult for farmers to correctly assess the nitrogen situation of their plants and make the corresponding amendments to the guidelines for using nitrogen fertilizers so as to obtain a large and high-quality harvest.

Traditional methods to determine the nitrogen contents of the soil and plants require significant amounts of labour and money to take samples and chemically analyse them. In practice, therefore, nitrogen fertilizers are often used without any consideration of the requirements of the crops being grown, which leads to a surfeit or deficit of nitrogen in the soil during the plants’ growing period. Therefore, introducing methods to monitor plants’ growth is one alternative way of using nitrogen fertilizers according to the needs of the plants.

There are many simple alternative methods which allow farmers to save money on buying fertilizer, increase harvest yields by using nitrogen fertilizer correctly and avoid unnecessary greenhouse gas emissions.

Many countries all over the world make successful use of a range of devices related to nitrogen fertilizer, such as the colour chart, chlorophyll meter, optical sensing device, etc. These devices enable the nitrogen situation of agricultural crops and soil to be assessed and allow the necessary dose of nitrogen that should be administered during the growing season to be determined. This substantially enhances the effectiveness of the current nitrogen guidelines and reduces the economic and ecological cost of using nitrogen fertilizers in agriculture.

The colour chart is a simple and cheap device (costing around 1 US dollar) that is suitable for use in the field. The colour chart sheet is made out of plastic and consists of six green sections of varying vividness. The amount of nitrogen in the plants is determined according to their colour. During the growing period of winter wheat, measurements using the colour chart are carried out by comparing crop leaves that are fully open. The nitrogen requirements of the plants are determined according to the “greenness” of the leaves, the type of leaf and the period of growth, and on this basis the necessary amount of nitrogen is calculated.

The chlorophyll meter SPAD-502[1] is both compact (it fits in your palm) and light (255 grams). Measurements of nitrogen content are carried out in the field on a fully-opened leaf at the top of the stem (see photo). Thus there is no need to tear or cut off the leaf from the plant, which allows measurements to be taken throughout the growing season without causing damage to the plants. The chlorophyll meter is easy to use and it informs the user of the nitrogen situation of the plant in real time, and if there is a deficit or surfeit. A farmer making use of the indications delivered by the chlorophyll meter could amend the nitrogen fertilizer guidelines during the crops’ growing season. One SPAD-502 chlorophyll meter costs 2,500 US dollars. Analysis has shown that a farmer who cultivates an area of 100 hectares could make back his/her investment in a chlorophyll meter in its first year of use, due to the more effective use of nitrogen fertilizers and the money saved on purchasing them.

The next method of assessing the amount of nitrogen in plants is the handheld optical sensing device called GreenSeeker. It not only enables a prediction to be made of the necessary dose of nitrogen to be added during the growing season of crops, but also monitors the development of above-surface biomass and delivers a predicted harvest yield. And it does not harm the plants: there is no need to take living samples from them.

Colour chart

Chlorophyll meter SPAD-502

GreenSeeker device

Specialists from the ZEF/UNESCO[1] project adapted GreenSeeker to the conditions of Uzbekistan and demonstrated the potential of using it effectively on the staple crops of Khorezm province.

Description of the invention

The GreenSeeker optical sensing device consists of an antenna, a pocket computer, a battery and a handle: it is therefore compact and only weighs around 6 kg. One person can easily handle the device while taking measurements. GreenSeeker emits infrared signals to measure the green parts of the plant, and the sensor picks up the reflected signals from the plant. The indicator displayed on the screen (vegetation index) allows the nitrogen situation of the crop under investigation to be determined. This device also makes it possible to measure how much biomass is above the surface in real time, which allows the harvest to be predicted. Experiments that have been carried out in test fields in Khorezm have demonstrated a high correlation (90%) between the amount of above-surface biomass and the harvest of winter wheat.

Advantages of the invention

The main achievement of the GreenSeeker optical sensing device is that it allows the nitrogen content of plants to be determined and corrections to be made when applying doses of nitrogen. All in all, GreenSeeker has the following advantages:

- simplicity and ease of use;

- great precision and operational measurements of the nitrogen content of plants in the field;

- it allows the necessary amounts of nitrogen to be used during the growing season to be determined;

- it measures above-surface biomass;

- it allows harvests to be forecast with an accuracy of up to 90%;

- it saves time and money;

- it brings ecological benefits due to the possibility of reducing the amounts of nitrogen.

Economic effectiveness of the invention

Depending on the model, one GreenSeeker optical sensing device costs between 250 and 7,000 US dollars. The savings brought by lowering the guideline amounts of nitrogen by using GreenSeeker are in Table 2. In particular, using GreenSeeker can help to determine the nitrogen content of winter wheat and, if necessary, reduce the amount of added nitrogen fertilizer (such as ammonium nitrate) by 50 kg, thus saving the farmer around 14,000 som. Converting this to an area of 100 hectares sewn with winter wheat, the savings could amount to 2.8 million som (1,800 US dollars).

Table 1. Savings on nitrogen fertilizer by using GreenSeeker

*The official exchange rate of US dollars to Uzb sum as of 29.06.2012, when these calculations were made, was 1,595 Uzb sums to 1 US dollar (Central Bank of Uzbekistan);
*ammonium nitrate was used as an example of nitrogen fertilizer (272.6 thousand Uzb sums per ton);
*the recommended amount of nitrogen for cotton plants is 200 kg per hectare, and for winter wheat is 180 kg per hectare.

External view of the optical sensing device

The effect of using the invention over an entire province. An extrapolation of the above calculations on the scale of an entire province also yielded impressive results (Table 3). In order to supply farmers in the Khorezm Province, for example, with chlorophyll meters, an investment of 2.6 million US dollars would be required, which would provide a return on investment within two years due to savings on the use of fertilizer.

Table 2: Effect of using chlorophyll meters over the whole of Khorezm

*100 hectares of sewn land require one chlorophyll meter

The use of chlorophyll meters in cotton fields in Khorezm Province would allow a reduction in nitrates of 2,700 tons if the guideline amount of nitrogen were to be reduced by 5%, and a reduction of 5,400 tons if the guideline amount were to be reduced by 10%, which would amount to 1.4 billion som (930,000 US dollars). The use of the same chlorophyll meter in wheat fields would permit a saving of 236 million som (148,000 US dollars) if the guideline amount of nitrogen were to be reduced by 5%, and a saving of 472 million som (296,000 US dollars) if the guideline amount of nitrogen fertilizer were to be reduced by 10%. Given that one GreenSeeker optical sensing device is required for 100 hectares, then, as the calculations show, an investment in GreenSeeker at its minimum price of 2,500 US dollars would pay off in its very first year of use, and would pay off in its fifth year of use if it was purchased at its maximum price of 7,000 US dollars.

As the calculations show, the use of the chlorophyll meter SPAD-502 and the optical sensing device GreenSeeker pay off, both for the individual farmer and for the entire province. Foreign countries have already started to produce cheaper versions of this device which hopefully suggests that Uzbekistan will make wide use of optical sensing in its agriculture. Investing in the acquisition of this device can pay itself off within between one and five years, depending on the initial cost.

Use of the optical sensing device in a cotton field

Conclusion

Calculations have shown that by using the chlorophyll meter SPAD-502 in farms with an area of 100 hectares a farmer can save up to $1,000 simply by making more sensible use of nitrogen fertilizers. In Khorezm Province as a whole, $930,000 can be saved on nitrogen fertilizers in cotton fields and $296,000 in winter wheat fields by using the SPAD-502.

In existing alternating crops (cotton-winter wheat/rice) in Khorezm Province, greenhouse gas emissions from annual crops on average amount to 6.8 kg of CO2 equivalent per hectare per day, or 2.5 tons of CO2 equivalent per hectare per year. Taking this as an average for the entire irrigated area of the country (4.3 million hectares), it is possible to calculate that annual emissions of N2O and CH4 amount to 10.5 million tons of CO2 equivalent. Thus, increasing the effectiveness of how mineral fertilizers are used in agriculture will permit a reduction in greenhouse gases.

In addition, the lack of necessary information, knowledge and contacts among farmers with regards to acquiring and using the different ways of determining the amount of nitrogen and its correct application is an obstacle to using this invention to make progress in agriculture. A possible solution to this problem is to make a centralized purchase of optical sensors by a authorized agencies (for example the khokimiyat – local administration – or the headquarters of the Ministry of Agriculture and Water Resources) in coordination with commercial banks so as to choose the best source of financing. It will thereby be possible to supply optical sensors in a ratio of one device per 100 hectares, which could then be leased to farmers.

For more information, please contact the non-governmental non-profit organization KRASS:

Contacts:
Yulduzoy Abdusharipovna Dzhumaniyazova
Candidate of Agricultural Sciences. Senior instructor, Urgench State University
E-mail: yulduz.d@gmail.com
Telephone: +99891 430 7623

Nazirbay Madrimovich Ibragimov
Professor, Doctor of Agricultural Sciences, Chief Scientist of the Agrochemical Laboratory at the Cotton Scientific Research Institute of Uzbekistan
E-mail: nazar.ibragimov@mail.ru

Jumanazar Sharipovich Ruzimov
Candidate of Agricultural Sciences, Lecturer at Urgench State University
E-mail: ruzimov_j@mail.ru
Telephone: +99891 434 9379

Jamila Umarovna Khaitboeva
Scientist at Urgench State University
E-mail: jamilahaitbaeva@rambler.ru

Izzat Rajabovich Kuryazov
Scientist at Urgench State University
E-mail: izzat_84@mail.ru

[1] The project tested the chlorophyll meter SPAD-502, although several other models and versions of the meter are used throughout the world.

[2] The ZEF/UNESCO project in Khorezm province in Uzbekistan has undertaken various thorough investigations that aim to make the use of nitrogen fertilizers on staple crops grown in the region more effective.