Soil Nutrition of Plants, 1957
SOIL NUTRITION OF PLANTS AND INCREASED AGRICULTURAL CROP YIELDS
*
T. D. Lysenko
*From a paper read at the September 15, 1953 session of the Lenin Academy of Agricultural Sciences of the U.S.S.R.

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The question of nourishing animals and plants is of paramount importance for agricultural science and practice. Everybody knows that the fodder supply is one of the main conditions for the development of stock-breeding. Soil fertility holds an analogous position with regard to plant-growing. The better the fodder supply the greater the amount of livestock products. The more fertile the soil the bigger the crops. The greater the yield of agricultural plants the more possible it becomes to establish a fine fodder supply for animal husbandry.

Fertilizing the soil provides suitable conditions for the nutrition of agricultural plants. This is very important for raising food and industrial crop yields and setting up an adequate fodder supply.

The decision of the September 1953 Plenary Session of the Central Committee of the Communist Party of the Soviet Union states the following with reference to fertilization:

*Measures of the Further Development of Agriculture in the U.S.S.R., Moscow, 1954, p. 40—Ed.

"One of the chief reasons for the low yields of cereal, oil-bearing and industrial crops in a number of areas of the country is that the soil does not receive sufficient organic and mineral fertilizer, particularly manure, peat and peat compost. Because of the lack of proper manure storage facilities in collective farms, the manure is improperly kept and loses its quality. In the Byelorussian S.S.R. and the Bryansk, Smolensk, Velikiye Luki and other regions, lupine, serradella and other green manure crops are planted to an extent far too small. In areas with acidic sod-podzol soils, most of the collective farms do no liming."*

On improving held fertilization the decision of the Plenary Session states:

"Accumulation and application of local fertilizers (dung, peat, liquid manure, compost, etc.) shall be more extensively practised. In regions where there are deposits of peat, its procurement for manuring and littering shall be increased. The preparation and application of composts and organic-mixtures shall be organized on a large scale, so that within the next two or three years the amount of organic fertilizer used by the collective farms will be one and a half times or twice as great as in 1952.

     "In 1954-63 the Ministry of the Chemical Industry and the Ministry of the Metallurgical Industry shall take measures to increase the mineral-fertilizer producing capacity to roughly 16.5-17.5 million tons in 1959, and to 28-30 million tons in 1964 (in terms of standard units). Output of granulated superphosphate shall be raised to 45 per cent of total superphosphate output in 1955 and to 60 per cent in 1958. From 1956 on, ammonium nitrate shall be supplied to agriculture only in granulated form. The question of broadly utilizing Khibini apatites and local phosphorites for agricultural purposes has to be investigated.

     "The U.S.S.R. Ministry of Agriculture and Procurements and the U.S.S.R. Ministry of State Farms and also the local Soviet and agricultural organs shall take measures to ensure the more efficient storage and utilization of mineral fertilizers, so as to prevent losses.

* Ibid., pp. 46-47.—Ed.

     "In view of the great importance of liming acidic soils and gypsuming saline regions as an important means of increasing crop yields, the Councils of Ministers of the Union Republics shall, beginning with 1954, take measures considerably to increase the production of lime for agricultural purposes by the plants of the building-materials industries, the local industries and the producers' co-operatives, and at the same time reduce the price of lime."*

The above statement shows the vast importance of fertilizing fields, as well as of liming acidic soils and gypsuming saline soils.

Yet the department dealing with this salient problem of the soil nutrition of plants—fertilization and liming—is in my opinion still the most backward department of agrobiology. Soil nutrition of plants is of such pre-eminent importance that even a minute scientific achievement in this sphere may and does exert a beneficent influence on the development of practical plant-growing and on various departments of agricultural science.

The problem of the soil nutrition of plants—i.e., of the nourishment obtained by plants from the soil—and of the use of fertilizer has hitherto been little worked upon scientifically; however, many scientific workers, such as plant-breeders and agrotechnicians, as well as agrochemists and biochemists, fancy that in the field of plant alimentation everything has already been clarified. But I am inclined to think that if certain men of science have no clear notion of what they do not yet know in their particular department of work, it is a sign that even what they do know does not reveal the essence of the processes going on in the phenomenon under discussion.

In actual fact even today agronomic biology has no biological conception of plant nutrition. In agronomy a purely chemical conception of plant nutrition is mistaken for a biological conception. According to the chemical conception, the process of soil nutrition consists in the absorption by the roots of anions and cations of water-soluble inorganic salts required by the plants in definite proportions. Thus the biological process of plant nutrition is still examined in agronomics from the chemical aspect only.

Chemists have already acquired in this regard considerable knowledge of great value and the chemical industry has begun to utilize this knowledge in manufacturing huge quantities of mineral fertilizer in forms that plants can assimilate directly. Practice has confirmed the theory that correctly applied mineral fertilizers are a potent factor increasing crop yields. But mineral fertilizers will beyond a doubt prove still more beneficial if the nutrition process of plants is investigated not only from the chemical aspect but also as a biological process, which in fact it really is.

I do not think any scientist will deny that animals and plants have much in common in their bodily structures and that these common features manifest themselves in their chemical and physical processes. However, science—here the physiology of animal nutrition—does not consider the latter merely a chemical process although the physiology of animals has been investigating quite a few chemical processes, and with success, too. Moreover, no one ever entertained the thought of giving animals only water-soluble

Herbivorous and omnivorous animals live on food the bulk of which is not water-soluble, although water-soluble substances are required for building up water-insoluble animal as well as plant bodies.

The building up and growth of animal and plant bodies from food take place in a chain of physiological processes and different food conversions, including the conversion of water-insoluble chemical substances into water-soluble ones.

Consequently, the nutrition of animal and plant organisms is a physiological process, a link in the general biological metabolism circuit in inorganic and organic nature. Everybody knows that physiological and, in a more general sense, biological processes always take place by the agency of chemical and physical processes. Biological processes are inseparable from physical and chemical processes. But it would be a mistake to reduce biological laws to chemical or physical ones, or to identify them.

Materialist science accepts it as an indisputable fact that physiological, hence biological processes take place on the basis of biological laws.

Agrochemists and biochemists must continue their fruitful research, must investigate the chemism of biological nutrition processes. The scientific work already referred to has been of use. But it has not revealed the biological laws of plant and animal nutrition. It discloses merely the chemistry of plants, the chemistry of foods and soils. The discovery of biological laws should be and has become the business of Michurinist agrobiology carried on in close contact with practical farming.

The biological laws governing the procurement of nutrients by plants from the soil find expression in the necessary interconnection between plants (or, to be more exact, between their root systems) and a definite complex of environing soil conditions. If the complex needed by a particular plant exists the latter normally satisfies its soil nutrition requirements.

Soil which possesses, in regard to both quality and quantity, the entire complex of conditions required by a given plant is regarded as good and fertile. Fertility is precisely the property which mainly distinguishes soil from bedrock. Academician V. R. Williams, the soil specialist, revealed more lucidly than anyone else the general laws of soil formation, the laws of soil development from elements of bedrock and of the atmosphere owing to the vital functions of micro-organisms, plants and animals. Taking as its basis the laws, already discovered by science and verified in practice, of soil development and of the development of the soil's main property, its fertility, the laws of the decline and restoration of the conditions of soil fertility, Michurinist biology must work out solutions for problems of practical importance in the sphere of soil nutrition for various agricultural plants.

The science of agriculture must pursue further its research into the biological, natural interconnections between plants and their soil environment—an essential factor of plant nutrition—and must use the results achieved as the basis for elaborating agrotechnical ways and means of improving plant nutrition, enhancing crop yields, facilitating farm work arid making it more productive.

I need not dwell in this paper on such universally known facts as that plants need soil moisture and that by diverse agrotechnical methods moisture is accumulated and saved as reserves in the soil or is removed from the soil if superfluous. Let us analyze the soil nutrition of plants from the angle of the natural interconnections between the root systems of the plants and the microflora of the soil.

MICRO-ORGANISMS AND PLANT NUTRITION

Soil scientists and scientific farmers have long been aware of the fact that among the conditions that determine the efficacious fertility of the soil there are conditions that make possible the vital functions of soil micro-organisms. Without the vital functions of appropriate soil micro-organisms the soil does not contain the food the plant requires. Consequently, in the absence of such favourable activity, the soul becomes a barren substratum for the plants in question.

As a result of the diverse influences exerted by the products of the vital activity of various soil micro-organisms, certain elements of inorganic and organic nature, which exist in a form unsuitable for plant nutrition, are changed into forms suitable for plant nutrition, and vice versa.

The vital activity of soil micro-organisms and their mutual interconnections as well as their interconnections with the root systems perform in the soil nutrition of plants the same function as the digestive system in animal organisms.

The organs and tissues of an animal organism feed on various substances which they need and which they absorb in an assimilable form from their digestive tract, which receives the food from the external environment in forms unfit for direct assimilation by the body of which the organs and tissues are part.

Thus it is the job of the digestive system to convert food from forms unfit for assimilation into forms that can be assimilated by the living body. In plant nutrition the same function is performed by the soil micro-organisms, which change the inorganic and organic elements and substances existing in forms unfit for assimilation by plants into assimilable forms.

Microbiologists have authentically established that in fallow sections, where the soil has been cultivated but not planted, the micro-organism complexes differ from those which inhabit similar soils but covered with vegetation. The complexes differ in respect to both quantity and quality.

In the root zones of plants there are more micro-organisms than in similar soil free from living roots. Besides, a number of species of soil micro-organisms display energetic vital activity, but beyond the root zone these species do not exist at all or their vital activity is greatly reduced.

We know that on the roots of all species of plants belonging to the leguminous family there are nodule bacteria assimilating nitrogen from the air. A specific species of these bacteria is characteristic for each species of the family mentioned. Neither the given leguminous species nor its specific nodule-bacteria species can develop normally without each other.

The same phenomenon has been observed also in many species of other families of herbaceous and arboreal plants, with whose root systems specific species of mycorhizal fungi are connected. In those cases, too, the plants feed badly and develop badly in the absence of mycelia on their roots specific for the plant species in question. Such plants and the mycorhizal fungi specific for them will not develop normally without each other.

There are also plants in regard to which neither the characteristic nodule bacteria nor the connected mycorhizal fungi have yet been brought to light. But in the zones of their root systems soil micro-organisms specific for these plant species have been ascertained.

The time has come when it is not only possible but, in my opinion, even necessary for general science and practice to lay down the proposition that there are natural interconnections between the root systems of all plant species and species of soil micro-organisms specific for each plant species or group of related species. Without such interconnections it is impossible for plants or the soil micro-organism species connected with them to feed or develop normally. Hence there are ample prospects of working out considerably more rational methods of fertilizing fields, of thus raising the yields of all crops, and of simultaneously improving soil fertility. Practice and science show that only by raising big crops every year can soils of low fertility be transformed into soils of high fertility.

Michurinist biologists realize that micro-organism species which normally cannot live outside the roots specific for these micro-organisms or without the root excretions of these plants, are also interconnected with other vitally necessary environmental factors of inorganic and organic nature. The same applies of course to the root system of plants. It has indispensable mutual connections not only with the species of soil micro-organism already ascertained but also with a number of others not yet ascertained, through whose enzymic action unassimilable forms of substances and elements of the organic, mineral and atmospheric environment turn into forms that the plants can assimilate.

Transformations of inorganic substances into organic and, vice versa, of organic into inorganic, can be effected only in a long chain of interconnections of biological species with one another and with their mineral and atmospheric environment, as well as with the dead organic matter. This is the circular course, the exchange of substances between living and non-living nature. The more fully science discloses the interconnections existing here, the easier will it be to work out agrotechnical ways and means of directing natural processes into channels leading to bigger crops of plant species we stand in need of. Differences obtained in organic and inorganic phenomena, objects, bodies are effected only by the difference in interconnections in the complicated chain of the process of metabolism (conversion of substances) in nature.

Changes in such interconnections bring it about that soils may improve or deteriorate, yields may rise or fall, certain plant and animal species may turn into other species, etc.

In the creation, in the soil, of nutrients for plants, in converting unassimilable and water-insoluble forms of elements and organic and inorganic substances into forms that plants can assimilate, the existence of specific complexes of soil microflora is, as has already been stated, the paramount factor for every species of plant and for every group of plant species. By setting up the conditions necessary for the normal vital activity of these complexes of soil micro-organisms we create the basis for soil fertility.

It often happens that soils of low fertility lack only a small group of factors essential for the normal vital activity of a complex of useful soil microflora. Practically only a trifle is missing in certain cases. And the agricultural plants cultivated on such soil go hungry and yield bad harvests only on account of that trifle. One need only remove this defect to bring about an improvement in plant nutrition and effect considerable harvest gains, while the soil becomes more fertile.

Carbohydrates, including cellulose, are essential elements of the life and nutriment of a number of useful soil micro-organisms, and part of the products of their vital activity is essential for feeding other micro-organisms. Therefore, when the soil contains, for instance, no carbohydrates (cellulose), there will be no development of the vital activity of even those useful micro-organisms which do not feed directly on cellulose and do not decompose it. Thus microbiologists have shown that if pure cellulose (filter paper) is converted into glucose by cellulose bacteria, other bacteria species (azotobacteria) turn atmospheric nitrogen by the use of glucose into ammonia nitrogen and organic nitrogen. Consequently, if the necessary conditions are provided, one may, figuratively speaking, by the use of a complex of microflora, transform cellulose (straw) into nitrogenous food for plants.

The examples cited prove that for the proper nutrition of agricultural plants and the simultaneous enhancement of soil fertility the important thing is that only the essential substances (fertilizers) should be introduced, and that the soil conditions now deficient but needed for the normal vital activity of the soil microflora promoting the plant's nutrition should be established. But there must be no full return to the soil of all the crop took from it. Agricultural practice must solve the problems of the soil nutrition of plants, taking into account the part played by the useful microflora in this process. Any other solution is economically unprofitable. Without the aid of corresponding soil micro-organisms it is difficult to nourish plants even with ready forms of food that can be assimilated. This can be done only in experiments with water cultures. Soils may contain, and as a rule do contain, great reserves of plant-food elements in water-insoluble forms and forms plants cannot assimilate. When the desired conditions exist these forms of substances are converted by the micro-organisms into food the plants can assimilate.

A scientific analysis of the various methods of tilling the soil, as applied in practical agriculture, and also the alternation of plants in crop rotations lead to the conclusion that both tillage methods and plant alternation in crop rotation greatly tend to create conditions that support the vital activity of micro-organisms promoting the soil nutrition of plants, and to suppress the vital activity of micro-organisms harmful to plant nutrition.

This is the point of view from which methods of treating soils with various mineral and organic fertilizers must be worked out.

But it does not follow in the least from what we have said that one should not use fertilizers ready to be assimilated by plants, such as, for instance, easily assimilated mineral nitrates and phosphates. All we said was that, in the main, plant nutrition takes place, and must take place, by the agency of the microflora, and therefore it is important that the latter should be ensured the necessary conditions, including the presence of the deficient nutrient elements in the particular soil.

In the non-chernozem regions a considerable portion of the soil suffers from an excess of acidity. In soil that is not strongly acidic its organic part (root and stubble refuse) and certain inorganic substances of the soil as well as the applied fertilizer are transformed by the pertinent micro-organisms into assimilable plant food.

On acidic soils, however, the vital activity of the microflora useful to agricultural plants is reduced. Soil bacteria, the products of whose vital activity serve as food for agricultural plants, usually do not inhabit the soil if its acidity exceeds a definite standard (usually when pH is lower than 4.5). Acid soils therefore hold little food fit to be assimilated by plants, in particular little nitrogenous and phosphoric food.

Experiments demonstrate that if it is possible to secure in some way or other the existence of food that agricultural plants can assimilate, the plants develop normally and become very hardy. Under such conditions clover and winter wheat overwinter in fine shape and yield big crops.

This indicates that in itself soil acidity is not injurious to agricultural plants or their root systems. The harmful effect of an acid soil environment on agricultural plants is due to the circumstance, already mentioned, that bacteria whose vital-activity products serve as food for these plants cannot live in it.

When mineral fertilizer is applied to acidic soils, conditions must be created in them that will make possible the vital activity of the micro-organisms that are of use to agricultural plants. Otherwise such an excellent mineral fertilizer as, for instance, superphosphate will become largely inaccessible to plants growing on acid soils.

In solving the problem of yield improvement on acidic podzol soils one should always bear in mind that it is the products of the vital activity of the micro-organisms that create the soil acidity itself, provided the soil does not contain calcium, which neutralizes this acidity.

Therefore on leaching (washing) calcium carbonate out of the soil the latter is somewhat acidulated by the acids which various micro-organisms generate. In general, soil acidity and alkalinity, in fact the entire soil is the result of the interaction of the vital activity of plants and micro-organisms on the one part and of the mineral elements of the bedrock on which the soil in question is formed on the other.

On lowering soil acidity by introducing lime as a neutralizing agent, a considerable improvement in agricultural-plant development may very often be observed.

This acidity reduction requires from 3 to 5 tons of lime and more per ha. But it has been established long ago by practice—and this is the most important thing—that unless simultaneously with the liming good crops of perennial grasses are raised on the acidic podzol soils, the acidity of such soils will, within a few years after the liming, return to the same level as before the liming.

It has therefore long been established practically and theoretically that when liming acidic podzol soils the latter must without fail be sown to good perennial-grass crops, which enrich the soil with organic substances. As such soils contain exceedingly small quantities of organic substances (essential food for useful soil microflora) and phosphorus, which plants can assimilate, the liming of acidic soils must be supplemented not only by perennial-grass (clover) sowing but also by dunging such soils and treating them with mineral fertilizer (superphosphate). If this is done fine integumentary grain crops and in subsequent years fine perennial-grass crops are obtained after liming.

A very small amount of nitrogen, sulphur and particularly phosphorus in a form that plants can assimilate is found in acidic soils because of the greatly lowered vital activity of the microflora. Hence the use of phosphorus fertilizer when liming strongly acidic soils and with less acidic soils even without liming is an absolute condition for obtaining good crops, especially of clover, lucerne and winter wheat.

But experience and practice have shown that the introduction of powdered superphosphates into acid podzol soil with and without liming is little effective. Phosphoric acid is as a rule almost wholly absorbed by the soil without any benefit to the plants. In these cases the micro-organisms, whose vital-activity products constitute an indispensable link in the chain of the biological processes of plant nutrition, are likewise unable to make use of phosphoric acid for lack of dead organic matter in the soil, matter that is essential to life for a number of micro-organisms, or the micro-organisms are unable to develop on account of the high acidity of the soil. Hence phosphoric fertilizer should be used for acidic soils in a form permitting the phosphorus to be utilized as quickly as possible by the useful microflora, whose vital-activity products the plants feed on.

Experiments have shown that the most rational way of treating acidic podzol soils, with or without liming, is to give them powdered superphosphate with at least a slight admixture of, say, humus or peat drenched with liquid manure, or, still better, with an admixture of good compost. However, powdered superphosphate not mixed with organic matter has little effect.

The high efficiency of superphosphate mixed, for instance, with a relatively small amount of humus or peat is due to the fact that nidi of microflora beneficial to the plants form around the bits of organic matter impregnated with the water-soluble part of the superphosphate.

In spite of the fact that the soil solution and the soil itself are acidic and therefore worthless as regards the life of the microflora, the acidity of the humus particles is not high. For this reason the bacterial flora of the soil, as a number of experimenters have shown, find around these bits of humus impregnated with the soluble part of superphosphate good conditions for their vital activities. Under these conditions plants cultivated even on comparatively acidic soil develop well, as they feed on the phosphorated products of the vital activity of the bacteria.

THE GORKI LENINSKIYE EXPERIMENTS

A centner = 100 kg

For the last four years about 120 kg. of superphosphate, mixed with 400-800 kg. of humus per ha., have been put into the loamy acidic podzol soils of the experimental farm of the Lenin Academy of Agricultural Sciences of the U.S.S.R. at Gorki Leninskiye, near Moscow, during the pre-sowing cultivation of soil under winter wheat. In spring they nourish the soil additionally with potassium and nitrogen fertilizer (4 centners per ha.). The resultant crops, with non-fallow preceding crops, registered 20-28 centners per ha. and with fallow predecessors 30-36 centners per ha. These figures are on a par with crops obtained on such soils with the land lying fallow and receiving 30-40 tons of manure per ha. Hence, in the above cases, 3 centners of superphosphate mixed with 1-2 tons of humus take the place of 30-40 tons of manure.

If powdered superphosphate is used without the admixture of 1-2 tons of humus or peat and the soil is not given any manure, then, other things being equal, winter wheat will yield a considerably smaller crop, usually not more than 10-15 centners. The frost-hardiness of winter wheat will also be considerably reduced, and this not infrequently ends in ruined crops in winter or in early spring.

Manure put on fallow fields in the amount of 30-40 tons per ha. was even in the distant past considered the best fertilizer for podzol soils and is still considered as such. It is well known that for such doses of this fertilizer liming is required only with strongly acid soils. Where they are of medium acidity and adequately manured, liming, if required at all, is done very sparingly, the dosage being 1-1.5 tons per ha.

But providing all podzol soils with big doses of manure at frequent intervals (best every year) requires, firstly, very much manure and, secondly, extensive transport facilities and means for delivering and evenly spreading the fertilizer over the field.

The quantity of good organic fertilizer can and must be considerably increased (it can and must be doubled and trebled) in comparison with the amount of manure obtained up till now. For this purpose extensive use must be made of the peat of up-river bogs for animal litters and the composting of down-river bog peat with manure, including liquid manure, must be considerably increased and improved.

Increasing manure and compost production and improving their quality are tasks of the utmost importance. They call for the mechanization of the production, drying, delivery, and spreading of organic fertilizers (manure, compost) over the fields.

Besides considerably augmenting manure and peat-manure compost output, we must also apply more mineral fertilizer, particularly lime and phosphorated fertilizer—superphosphate, as well as ground phosphorite. We consider it must advisable to put on lime and mineral phosphoric fertilizers after mixing them with organic fertilizers. Proportions of the components of such mixtures, dosages, time of application and soil depths will be discussed below.

The experiments performed in 1953 by Academician A. A. Avakyan on the experimental farm of the Lenin Academy of Agricultural Sciences of the U.S.S.R. at Gorki Leninskiye fully confirmed the great importance of correctly using fertilizer to increase crops in the non-chernozem zone. Let me quote a few experiments with winter wheat (see table).

Experiment with Winter Wheat 1160 at Gorki Leninskiye in 1952-53

Quantity of fertilizer used per ha. C r o p
(in centners
per ha.)
10 t. lime* 22.2
10 t. lime + 3 centners superphosphate 24.0
5 t. lime 22.6
5 t. lime + 3 centners superphosphate 25.2
control 17.8
1.8 t. humus 24.1
1.8 t. humus + 3 centners superphosphate 27.4
3 centners superphosphate 22.0
1.8 t. humus + 3 centners superphosphate + 3 centners lime 28.7
3 centners lime 19.9
1.8 t. humus + 3 centners lime 27.3

* Ground limestone.

In the experiment under discussion, winter wheat was sown in the autumn of 1952 on unfallowed land after barley as a preceding crop. The soil was podzol with rather high acidity. From plots not fertilized before sowing 17.8 centners of wheat per ha. were obtained. But plots fertilized before sowing with 1.8 tons of humus mixed with 3 centners of superphosphate and 3 centners of ground limestone yielded 28.7 centners of wheat per ha.

Consequently, owing to the small doses of the fertilizer mixture, the excess crop amounted to 10.9 centners per ha. It may be retorted that in this case quite a bit of superphosphate—3 centners per ha.—was used.

But when the same experiment was performed on two other plots which were given 3 centners of pure superphosphate per ha., i.e., not mixed with humus and lime, the crop was equal to 22 centners of wheat grain per ha., i.e., 6.7 centners less per ha. than was obtained from the plots on which the same amount of superphosphate, namely 3 centners, was used, but with an admixture of 1.8 tons of humus and 3 centners of ground limestone. The plots that were given 1.8 tons of humus mixed with 3 centners of superphosphate but no lime yielded 27.4 centners per ha.

The most interesting point in this particular experiment is the finding that plots given 1.8 tons of humus per ha., mixed with 3 centners of lime, without the addition of superphosphate, yielded the same good crop, namely, 27.3 centners per ha., i.e., 9.5 centners more per ha. than plots that did not receive any fertilizer.

Such experimental results compel every scientific worker, every agronomist, to draw the conclusion that the effect will be considerably greater if phosphoric fertilizers (ground phosphorite and powdered superphosphate), as well as lime fertilizers, are introduced into podzol soils not in their pure form but invariably mixed with at least small amounts of organic fertilizer.

As a matter of fact, if in the pre-sowing cultivation of the soil for winter wheat 1.5-2 tons of organic fertilizer mixed with 3 (better 5) centners of limestone material are introduced, the grain crop may be increased in weight by half the dosage of the cheapest agricultural fertilizer put in the soil.

The importance of employing lime mixed with organic fertilizer becomes apparent from the fact that plots which in this experiment were given the same dose of 3 centners of lime not mixed with organic fertilizer produced only 19.9 centners per ha., while plots which received 5 tons of lime per ha. not mixed with organic fertilizer produced 22.6 centners of wheat per ha.

Hence the introduction per ha. of 3 centners of ground lime mixed with 18 centners of humus had a much better effect than putting in 50 centners of ground lime without the addition of any organic fertilizer. In the first instance the crop registered 27.3 centners per ha., in the second, 22.6 centners.

As already stated, at Gorki Leninskiye a mixture of organic fertilizers and mineral phosphoric fertilizers without any addition of lime has been introduced for four years now into the pre-sowing cultivation of land for winter crops planted for production. This four-year production experiment has fully confirmed the advisability and great effectiveness of this method.

It should be noted that on control and experimental plots, the nitrogen and potassium background was on a par in the production crops. The usual dose was one centner of nitrogen and of potassium fertilizer per ha. Every year some of the autumn-ploughed fields were limed. Sometimes lime was spread over sown clover.

And now I shall explain the results of some production experiments obtained in 1953 with regard to the application of superphosphate mixed with humus.

A 5-ha. section of land that had produced a crop of spring wheat was sown in the autumn of 1952 to winter wheat. On a plot of 0.5 ha. no fertilizer was used before sowing. The cereal crop produced by this plot amounted to 20.3 centners per ha. A neighbouring plot, also 0.5 ha. in size, was given, before sowing, 3 centners of powdered superphosphate per ha. Here the yield was 27.3 centners per ha. Along one side of these plots a section holding 1.8 ha. was situated and along the other side there was another section of 2.2 ha. Both sections were treated during the pre-sowing cultivation with a fertilizer mixture consisting of 1.5 tons of humus and 3 centners of superphosphate per ha. The crop obtained from the first section amounted to 34.3 centners per ha. and from the second to 39.3 centners per ha. So in this experiment too a superphosphate mixture with only 1.5 tons of humus resulted in a crop excess of 7 centners of winter wheat per ha. on the one section and of 12 centners on the other section, if the yields are compared with those of land on which only superphosphate was applied.

On another plot, comprising an area of 11.5 ha. and considerably less cultivated than the previous one, the following bunker crop of winter wheat was obtained: From 1.5 ha. over which no fertilizer was spread the grain yield was 10 centners per ha. An adjoining section of 1 ha., in which 3 centners of powdered superphosphate were inserted before the ground was cultivated for sowing, produced 14.6 centners per ha. Alongside these two sections there were two other sown fields, one of 2.7 ha. and the other of 6.3 ha., on which during the pre-sowing cultivation the following mixture per ha. was introduced: 3 centners of powdered superphosphate and 15 centners of humus. The 2.7 ha. section grew 23.4 centners per ha., the 6.3 ha. section 21 centners per ha.

Thus we see that in this case too the introduction during the pre-sowing cultivation of 3 centners of superphosphate mixed with 15 centners of humus per ha. increased the crop in the one instance by 6.4 centners and in the other by 8.8 centners per ha. when compared to crop yields on sections treated with pure superphosphate. It should be clear to everyone that if in this experiment at least 3 centners of limestone fertilizer had been added to the above mixture of 1.5 tons of humus and 3 centners of superphosphate per ha., the results would have been still better. The experiments show that very effective results are achieved by the introduction into podzol soil of mixtures not only of superphosphate and lime plus organic fertilizer but also of ground phosphorite with organic fertilizers—humus, rotten manure or peat suitable for fertilization.

FERTILIZE ALL FIELDS UNDER CROP

Taking the above as our premise we recommended that in 1953 the collective and state farms should widely check the experiment of introducing mixtures of organic fertilizer with mineral phosphoric and lime fertilizers for winter crops during their pre-sowing soil cultivation. It was recommended to introduce these fertilizers into fields that had not been fertilized.

Among phosphoric fertilizers we suggest superphosphate and ground phosphorite; among limestone fertilizers: ground limestone, marl and ground dolomite.

The following fertilizer dosages per ha. may serve as models, their choice depending on the specific conditions and possibilities of the farm: 1.5-3 tons of organic fertilizer (humus, rotten manure or peat suitable for fertilizing); 2-3 centners of superphosphate or 3-4 centners of ground phosphorite, or preferably 0.5-1 centners of superphosphate plus 2-3 centners of ground phosphorite; limestone fertilizer—3-5 centners.

If there is no limestone fertilizer on the farm and none can be procured before the sowing, organic fertilizer mixed only with phosphoric fertilizer may be used. If, on the contrary, there is no phosphoric fertilizer on the farm but there are lime ones or the latter can be procured before the sowing, the organic fertilizer must be mixed with the limestone fertilizer.

The measures we have devised amount essentially to the creation of conditions favourable for the vital activity of the micro-organisms of the soil. The products of the vital activity of these organisms, which inhabit the young root zones, are essential for normal plant nutrition. The mixtures we recommend of organic and mineral phosphoric and limestone fertilizers are needed as food for the micro-organisms living in the zones of the young roots of agricultural plants. In podzol and particularly acidic soils these micro-organisms do not find adequate food and other conditions for their development. In consequence plants growing on such soils starve: on the one hand, because there is a lack of the products of the vital activity of micro-organisms living in the root zones end constituting essential elements of the complex of root nutrition of the plants; on the other hand, because some of the products of the vital activity of root micro-organisms are essential nutritive elements for micro-organisms existing outside of the root zone and transforming by their enzymic activity forms of matter unassimilable by roots into assimilable forms.

This explains why the fertilizer mixture we suggest must be applied not a long time before sowing, but about 1-5 days before the pre-sowing soil cultivation, and must be introduced into the soil not at a depth of 15-20 cm., but at that of the seed-bed, i.e., at the depth at which the soil of the pre-sowing cultivation becomes friable.

In brief, the proposed measures aim at receiving good crops on sections of low fertility and at converting low-fertility soils into high-fertility soils by means of good crops, particularly of perennial grasses.

The theoretical principles of the developing Michurinist biology and the results of the experiments performed by the Lenin Academy of Agricultural Sciences of the U.S.S.R. by a consensus of opinion have predicted a great future for the proposed method of applying fertilizers, particularly on podzol soils.

The mixing of fertilizers and their even spread over the fields before the pre-sowing cultivation can easily be mechanized. Samples of such machines are already available. Manure and mineral-fertilizer spreader TUR-7 makes a good job of mixing organic with mineral fertilizers and spreading them over the fields. With this machine and a loader, 3 people can easily mix and spread enough fertilizer in one day for 10-15 ha., at the rate of 3-5 tons per ha.

The main thing is to convince agronomists and collective farmers by their own experience that the introduction before sowing at seed-bed depth of small doses of organic fertilizer enriched by mineral phosphoric and limestone fertilizers is on podzol soils several time, as effective as when the same fertilizers are applied separately, or at different periods or depths. So long as the different localities have no machines for mixing and spreading, these operations will have to be performed by hand. The mixing may be done with shovels and the spreading with the aid of lorries or carts moving across the field. The fertilizer should be covered up by pre-sowing cultivation or disking.

I have already stated that if a particular collective or state farm has no humus, peat suitable for fertilization may be taken for mixing with phosphoric and limestone mineral fertilizers. Before peat can be used to prepare a mineral fertilizer mixture it must be drenched with liquid manure, which introduces into the peat the necessary microbic ferment. Peat may be mixed with rotten manure. In that case the liquid manure may be dispensed with.

Agronomists, collective farmers and state-farm workers in the non-chernozem belt displayed great interest in the Lenin Academy's fertilization scheme.

Unfortunately, the Ministries of Agriculture and of Agricultural Stocks of the U.S.S.R. during the winter grain sowing in 1953 did not afford the requisite assistance to the collective and state farms. They failed to supply them with limestone and phosphoric fertilizers, and likewise did not provide adequate organizational aid for carrying out this important measure.

It is necessary that as early as in the spring of 1954, both in the scientific research network and in the collective and state farms, extensive experimentation for production purposes should be instituted, whereby mixtures of organic with mineral phosphoric and limestone fertilizers should be applied to spring crops and to various agricultural plants, as well as to fruit and berry plantations. These fertilizer mixtures should, beginning with the spring of 1954, be used on a particularly wide scale in the square-pocket sowing of potatoes and vegetables.

Advanced collective farmers are already applying locally organic fertilizers mixed with mineral phosphoric fertilizers in the square-pocket sowing of potatoes and vegetables, and the results have been good. Organic fertilizers should also be mixed with limestone fertilizers.

The Academy's 1953 experiments showed that a fertilizer mixture composed of 3-7 tons of rotten manure or peat plus 2-3 centners of superphosphate and 3 centners of limestone material per ha. introduced into the pockets in the square-pocket planting of potatoes or into the planting furrow in row planting, results in a considerable increase in the potato yield.

Similar good results are obtained in experiments with such vegetables as cucumbers, cabbage, etc.

In the square-pocket sowing of cucumbers and the planting of cabbage and tomato seedlings, at least 200-300 grammes of the fertilizer mixture indicated must be introduced into every sowing and planting pocket. This will raise the crop yield no less than the use of 40 tons of manure per ha. right before ploughing.

Very good results follow the planting of vegetables (tomatoes, cabbage and cucumbers) in earthen peat-and-humus pots, not only because plants in such pots do not suffer when transplanted into the field but also because in these pots there is nutrition for the development and vital activity of the micro-organisms that are the principal link in the soil nutrition of plants.

There are grounds for assuming that the application of organic fertilizers mixed with. mineral phosphoric and limestone fertilizers will be the best means of fertilizing citrus plants in the subtropical districts of the Georgian Soviet Socialist Republic.

Proper nutrition of citrus plants will be one of the measures used in combating the mal secco disease in lemon plantations. In this sphere Comrade Shanidze (Batumi Botanical Gardens) has achieved promising results.

No more than 5-10 kg. of a mixture of organic fertilizer with mineral phosphoric and limestone fertilizer need be introduced under each citrus or other fruit tree. It is best to introduce it under every tree in nests (3-5 holes 10-20 cm. deep).

In the Soviet Union the mineral fertilizer supply to the fields was improving each year. Now the decision of the September 1953 Plenary Session of the Central Committee of the Communist Party of the Soviet Union envisages an increase in output of mineral fertilizer and limestone material equal to several times the former output in order to provide for the country's agricultural needs. It is further contemplated to increase sharply the production and accumulation of organic fertilizers: manure, peat, peat compost and peat-and-manure compost. Soviet agriculture will be receiving huge quantities of various machines required for its organic and mineral fertilizer programme.

This gives rise to an unprecedented demand for more and more rational methods of using fertilizer so as to enlarge crop yields in all the fields of our country. At the same time it opens up new and wide avenues for the development of soil biology, the science treating of the soil nutrition of plants (the fertilization of fields).

The decision of the September Plenary Session points out that many scientific research institutes and experiment stations carry on their work divorced from practice, lock themselves up in their laboratories, keep aloof in their experimental fields, and fail therefore to enrich science and practice with new discoveries and proposals. They are thus of little help to the collective farms, machine-and-tractor stations and the state farms in improving methods of tillage and animal husbandry. The fundamental principle enabling science to develop—unity of theory and practice—has been violated. Deep theoretical problems of the development of living nature must always be solved with an eye to the settlement of practically important issues, making use of the unprecedented possibilities created by the Party and the Government for the development of science. Science cannot develop with any success without daily propaganda and the penetration of the achievements of science and of advanced scientific experience into the sphere of production. The Plenary Session raises this issue alongside other important issues that must be decided so as to be able to cope with the problem of bringing about a steep rise in the level of agriculture in our country. The Academy and its institutes, and the workers of the entire network of agricultural research must revise the programme of their work in the light of the decisions of the Plenary Session. When fulfilling practically important tasks of collective- and state-farm plant-growing and animal husbandry, we still do not make adequate use of the achievements of theoretical Michurinist biology. This hampers the further development of the theory of Michurinist biology.

Workers in the field of agricultural science in close unity with the foremost representatives of collective- and state-farm production must put an end to the lagging of the science of agriculture behind the steadily mounting demand for increased production. We are fully able to do so. There can be no doubt that the scientific workers in agriculture will make use of that tried and true means of eliminating shortcomings in work—criticism and self-criticism, and that the science of agriculture will take its proper place in implementing the decisions of the September Plenary Session concerning the new powerful advance of agriculture in our country.