FIELD EXPERIMENTS AND THEIR IMPORTANCE IN THE AGROCHEMICAL SERVICE

N. F. TYUMENTSEV, O. L. KURYLEVA, L. K. TSYTSAREVA

The State Agrochemical Service began to be established in Western Siberia in 1964, and in Tomsk Oblast only in 1965.

By this time preliminary studies of the fields of the “Tomsky” state farm had been carried out, various methods of agrochemical mapping had been tested [8]. At the conference on chemicalization, the content of agrochemical work was discussed [6]; agrochemical cartograms for microelement composition were compiled and tested [1]; for production-methodological purposes, an inventory of peats was carried out at the “Tomsky” state farm [7].

A favorable prerequisite for the development of the agrochemical service should also be considered the systematization of all materials from the soil survey of the lands of collective and state farms according to the qualitative assessment of soils [4], and the summary reports on the long-term study of the action of fertilizers in field experiments [2, 5].

The availability of new methodological manuals on agrochemical work [3], the equipping of the oblast agrochemical laboratory with modern instruments, glassware, and reagents, and staffing with specialists contributed to the fulfillment of the field-work plan in 1965.

The experience of the first year showed that an agrochemical laboratory must not only conduct agrochemical soil surveys and compile agrochemical cartograms, and set up field experiments, but also exercise control over the use and application of all types of fertilizers, and identify and study local fertilizers.

All these works are closely interconnected and constitute links in a single system of the agrochemical service.

Agrochemical materials make it possible to clarify the state of soil fertility and to take appropriate measures to eliminate the detected deficiencies in the content of nutrients and soil humus by applying fertilizers.

Regardless of the possibility of purchasing mineral fertilizers and of the completion of agrochemical surveys, the agrochemical laboratory is always obliged to provide constructive recommendations concerning soil fertilization. Data from previous and new field experiments and a systematic inventory of local fertilizer reserves—including manure, humus, ash, lime, vivianites, and peats—help to fulfill this requirement.

Without touching on all these questions, we shall dwell only on field experiments and on the identification of local fertilizers.

In 1965 the oblast agrochemical laboratory carried out a soil survey on six farms with different soils over an area of 68 thousand hectares. At the same time, 9 field experiments were established: 7 with wheat, 1 with corn, and 1 with flax. Only 5 experiments with wheat were recorded and recognized as reliable. For comparison of the results when summarizing the data, the results of a field experiment of the oblast experimental station on leached chernozem were also used.

All experiments of the agrochemical laboratory were laid out according to a five-treatment scheme (O, NP, NK, PK, NPK) in four replications, with an accounting-plot area of 100 sq. m and buffer strips 1 m wide between plots.

The agrotechnical background consisted of autumn plowing, early spring harrowing, and cultivation. Mineral fertilizers—nitrogen and potassium—were applied at the rate of 45 kg, and phosphorus at 60 kg of active ingredient per hectare, by hand and incorporated with harrows. Sowing was carried out with tractor seeders, using high-quality seed of the varieties “Skala” or “Diamant.”

During the summer, weeding was carried out where required; emergence density was recorded, and in some experiments the stem density before harvest was also recorded. Harvesting for the main accounting was done by combine, and for control by trial sheaf. After processing, the combine-harvest data for wheat were recognized as the most accurate. On leached and podzolized chernozem, three experiments were recorded (the villages of Batkat, Kargala, and Kozhevnikovo); on gray forest soil, three (Kozhli, Takhtamyshevo); and on light-gray soil, one (Vysokii Yar).

A feature of the meteorological conditions of the 1965 growing season (May, June, July) was the occurrence of a drought unprecedented for Tomsk Oblast. Mean temperatures and precipitation for the most critical months of the growing season in 1965 deviated sharply from the long-term averages for the same period (Table 1).

Table 1

Deviation of mean temperatures and precipitation during the growing season (May–July) in 1965 from long-term averages, in %

Under such conditions of the principal meteorological factors, wheat yields were low; nevertheless, at all sites, under the influence of mineral fertilizers, they increased on all soils.

The positive effect of fertilizers was evident in an increase in emergence density: on podzolized chernozem by 22%, on gray forest soil by 25%, and on light-gray forest soil by 6% compared with the density on the same unfertilized soils.

An even more marked increase in stem density was observed by harvest time: on gray forest soil by 32% and on light-gray soil by 14%.

The plot data for the wheat grain yield, adjusted to 16% moisture content and absolute purity, were processed mathematically and then

were used to calculate the mean values for each of the treatments (Table 2).

The conclusion from this table is definite: under drought conditions, on all soils, mineral fertilizers provide substantial increases in the grain yield of spring wheat both on leached chernozem and on gray and light-gray forest soil.

Table 2

Grain yield of spring wheat in experiments with mineral fertilizers
in the drought year 1965, in centners/ha

But if spring wheat responds well to fertilization, then winter rye and oats should be still more responsive, as has been shown in the long-term field experiment of the Tomsk Regional Station.

All nutrient elements on the three main soil types increased the yield by a substantial amount.

From the summarized data in Fig. 1 it is easy to conclude that the effect of complete mineral fertilizer (NPK) increased regularly—on gray soil by one and a half times, and on light-gray soil by two times, compared with its effect on leached chernozem.

Among the components of the complete fertilizer, the role of phosphorus was especially clearly manifested on chernozem and on gray forest soil, and that of nitrogen on light-gray soil.

A significant yield increase was provided by nitrogen fertilizer on chernozem (1.1 centners) and on gray forest soil (1.7 centners), and by phosphorus fertilizer on light-gray soil (1.6 centners/ha).

In connection with the revealed positive effect of mineral fertilizers in a drought year, it is interesting to note that in preceding years, typical in terms of meteorological conditions, the yield increases in the experiments differed little from those given above, as follows from Table 3.

A substantial difference is noted only on gray forest soil. It is interesting that in years with optimal meteorological conditions, as in 1964, the increase in wheat yield from complete mineral fertilizer was twice as high in the experiments of the Tomsk Experimental Station on leached chernozem and reached 4.2 centners per ha.

Mineral fertilizers are used more often than organic fertilizers in experiments to study the degree of soil fertility.

But it may be considered that such experiments pave the way for organic fertilizers as well.

Previous experiments in Tomsk Oblast have shown that manure and peat-manure compost, as fertilizers, act almost the same as mineral fertilizers in the first year of application.

Fig. 1. Increases in the grain yield of spring wheat from the application of mineral fertilizers in the dry year 1965 on leached chernozem (I), on gray forest soil (II), and on light-gray forest soil (III).

At the same time it was established that organic fertilizers are distinguished by their ability to increase yields for up to six years after a single application.

Table 3

Magnitude of increases in wheat grain yield from mineral fertilizers (NPK), c/ha

Organic fertilizers increase soil fertility to a greater extent than mineral fertilizers.

That is why it is necessary to supplement mineral fertilizers with organic ones, or to alternate their application by year.

Therefore, in the very first year of agrochemical surveys, measures were taken to determine the yield of manure on the farms surveyed, and to determine reserves of humus and peat.

The yield of manure is determined by familiar methods—according to norms or by the number of livestock.

The reserve of humus in tons per hectare is determined from the area and the average depth of the deposits. From these data the volume is calculated, and after introducing a correction (0.7–0.9), the weight in tons.

Identifying peat reserves is a much greater concern. These works were first carried out at the “Tomsky” state farm.

The starting point in the inventory of peats is a soil survey, completed by a qualitative assessment of the soils. During the survey, areas of waterlogged soils are identified and subjected to additional study.

Thus, at the “Tomsky” state farm, 29 peat deposits were identified over an area of 977 ha, with reserves of up to 7 million cubic meters of peat.

The inventory of peat bogs must be carried out not only in order to identify the total reserve of peat. The point is that peats occur that differ sharply in their qualitative condition: in degree of decomposition, in botanical and chemical composition, and in accessibility for development.

Depending on the quality of the peat, it will be used differently on the farm: for composts, for bedding, or directly as fertilizer, or it will be used for development into agricultural land.

In rare collective and state farms of Tomsk Oblast are there no peat bogs. Their total area reaches 212 thousand ha. Surveying such an area is connected not only with studying the quality and reserves of peats for agrochemical purposes and for animal husbandry; the area itself is also of economic interest. After all, in time they may add to forage lands and arable land.

In 1965, during the first large-scale agrochemical mapping, peat bogs in some farms were surveyed. The samples will be analyzed in order to draw conclusions about methods of using peat on farms.

When setting up certain experiments with mineral fertilizers in 1965, mixed soil samples were taken from each plot in order to compare the results of agrochemical soil analysis with the results of field experiments. The data obtained (Table 4) show that there is a definite relationship between increases in wheat yield from fertilizers and the corresponding agrochemical data.

Table 4

Relationship between yield increases and agrochemical indicators

The yield increases from potassium and phosphate fertilizers are consistent with the agrochemical indicators. Let us recall that, when determining mobile potassium, a K₂O content of less than 14 mg per 100 g of soil means—

has low availability; 14–20 mg—medium, and more than 20 mg—elevated.

The degree of phosphorus availability within the range of 10–20 mg per 100 g of soil is considered medium. In all three cases, yield increases of 1.6 to 2.5 centners/ha from phosphorus fertilizer are of economic interest.

There is no point in looking for the reason for differences in yield increases under identical agrochemical indicators, since it is practically impossible to take into account all the nuances of local natural and economic conditions.

We believe that it is quite sufficient to obtain an overall picture of the agreement between yield data and agrochemical indicators. Agrochemical indicators may be regarded as a sufficiently objective measure for drawing conclusions about the need to apply fertilizers.

Here we are not yet addressing the dependence of fertilizer rates on the results of analysis. In time, the agrochemical laboratory will come to consider this question.

Literature

1. V. E. Andreevskaya, N. F. Tyumentsev. The content and distribution of microelements within a single field. In: Questions of the Chemicalization of Agriculture in Tomsk Oblast. Proceedings of Sib. Publishing House, Tomsk, 1965.

2. T. T. Vilesov, N. F. Tyumentsev. Experiments on the use of organic and mineral fertilizers on gray forest soils. Tomsk State University Publishing House, 1961.

3. A. V. Sokolov. A Guide to the Compilation of Soil and Agrochemical Maps. Kolos Publishing House, Moscow, 1964.

4. N. F. Tyumentsev. Qualitative Evaluation of Soils and the Methodology for Conducting It. Tomsk Book Publishing House, 1962.

5. N. F. Tyumentsev. The role of fertilizers in field cultivation in the non-chernozem zone of Western Siberia. Tomsk State University Publishing House, 1963.

6. N. F. Tyumentsev. On the agrochemical service in Tomsk Oblast. In: Questions of the Chemicalization of Agriculture in Tomsk Oblast. Proceedings of Sib. Publishing House, Tomsk, 1965.

7. N. F. Tyumentsev, L. V. Morgunov. Economic characteristics of the peat soils of the “Tomsky” state farm. In: Proceedings of the Tomsk Experimental Station. Proceedings of Sib. Publishing House, Tomsk, 1966.

8. N. F. Tyumentsev, L. K. Tsitsareva. From the experience of field agrochemical studies. In: Reports of the Conference on Chemicalization. Tomsk State University Publishing House, Tomsk, 1969.