4. Practices of soil amendment and land use improvement in the arid steppe zone.

Arid steppe zone is reclaimed for agriculture approximately by 60%. Before the development of irrigation in the 60s, the yields of crops were unstable. But irrigation, if practiced just a bit inconectly, is frought with a multitude of soil degradations. Various practices of soil conservation are important on irrigated lands of the arid steppe zone: those directed to stop irrigation erosion, drainage to prevent the water losing and swamping of soil, and those aiming to improve the irrigation water quality. On dark chestnut soils the irrigation can be effective provided sufficient rates are applied of organic manures and mineral fertilizers. To improve chestnut sodicity affected soils, a deep plowing is needed, especially on the soils with shallow “placement” of a gypsiferous horizon. Regular gypsum applications should accompany the use of fertilizers. With irrigation these practices give better result.

Solonetz soils lie in spots which makes it difficult to improve them. The practices used are the same as those for the dominating soils. We in Ukraine still farm by the field, not by the soil. It localities with shallow depth of a gypsiferous horizon, deep plowing with application of large rates of farm manure may be effective. Gypsum rate (mt/ha) for any sodicity-affected or sodic soil should be computed by the formula:

GR, mt/ha=0.086 (Na⁺-0.05CEC) h · d ,

where Na⁺ is the exchangeable sodium content in m.eq per 100g of oven dry soil;

CEC = cation exchange capacity of soil in a layer to be improved;

h = depth of a layer, cm;

d = the bulk density of a soil in this layer, g/cm³.

Management of salt-affected soil once centred around the maintenance of salt balance for a given field or irrigation project. The quantity of salt entering the area should not exceed the quantity of salt leaving the area. Some soils may be leached from the soluble salt. To calculate the leaching requirement of water one may use the simple formula proposed by V.R. Volobuyev:

LR, m³/ha = 10.000·h··log (C_actual/C_desirable) ,

where h is then depth of a layer which is to be leached from the excess of soluble salt, m;

 is a dimension less parameter called a coefficient of salt yielding, which fluctuates within 0.66-3.3 depending on soil texture and the nature of salts causing salinity;

C_actual and C_desirable are the concentrations of soluble salts in % which as the names imply are actually present in the layer and which are desirable to remain after leaching for economically feasible soil improvement. The American textbook of soil chemistry (H.Z.Bohn, B.L.McNeal and G.A.O’Connor) states that the passage of 1m leaching water m^-1 soil depth under ponded conditions normally removes approximately 80% of the soluble salt from soil³.

A more efficient leaching technique is the basin-furrow method. The soil is nearly leveled and irrigation water is allowed to meander back and forth across the field through adjacent sets of furrows. The water may take as long as a week to meander across the entire field under such conditions, but the quantities of water required are less than for ponded leaching.

Enough Ca²⁺ must be present in water during the reclamation of sodic soils. The equivalent concentration of magnesium in water should not exceed that of calcium.

LITERATURE

Essential Sources:

1. Гнатенко О.Ф., Капштик М.В., Петренко Л.Р., Вітвіцький С.В. Ґрунтознавство з основами геології. Навчальний посібник. Київ. Оранта. 2005. – 423 с.

2. Methodological Instruction Book “Elements of Geology”. Petrenko L.R., Kravchenko Y.S., Starodubtsev V. M. Kyiv.2005.-98 p.

3. Methodological Instruction Book “Soil genesis, classification, nomenclature & diagnostics”. Petrenko L.R., Kravchenko Y.S., Baydyuk M.I. Kyiv.2006.-50 p.

4. Foth H.D. Fundamentals of Soil Science. 8E. John Wiley & Sons. New York. Brisbane. Toronto. Singapore. 1990.- 360p.

5. Hilled D. Introduction to Soil Physics. London, Toronto: Academic Press, Inc.1982.-365 p.

6. Bohu H.L., Mc Neal B.L., & G.A.O’Connor. Soil Chemistry.2^nd Edition. N.Y.John Wiley & Sons. 1985.-341 p.

7. Mc. Bride M.B. Environmental chemistry of Soils. New York.

8. Oxford. Oxford University Press. 1994.-406 p.

APPENDIX 1.

Subject-matter of soil science:

1. soils, their origin, constitution composition and properties;

2. regularities of soil geographic distribution;

3. processes of soil interaction with the environment determining the formation and development of their essential property – fertility (productivity);

4. ways and practices of soil use and management in agriculture and other branches of human activity and the practices of soil conservation;

5. the evolution of soils under anthropogenic impact.

Fertility in our textbooks (Williams):

The soils ability to satisfy the requirement of plants in nutrients and water and to supply their roots with sufficient amount of air and heat for normal growth, development and yield formation.

Up-to-date definition of soil (Rozanov,1975)

Soil is a complex polyfunctional open four-phased structured system in the surface part of cortex of weathering which is also a complete function of parent material, organisms, climate, relief and time and which is endowed with fertility (productivity)

APPENDIX 2.

ДСТУ 3980-2000

ҐРУНТИ : ТЕРМІНИ ТА ВИЗНАЧЕННЯ.

SOILS: TERMS ND DEFINITIONS

SOIL is a historically developed natural organic-mineral body which arose on the surface of the Earth’s crust as a result of long-time interaction of biotic, abiotic and anthropogenic agents, has specific genetic-morphological features and properties the most essential of which is soil fertility.

1 By the thory, advanced by K.K.Gedroitz’ solonetz’ formed from leaching of saline soils, containing neutral sodium salts and solot soils (solod soils) formed from solonetz’ leaded farther by water containing CO₂ as a result of partial substitution of exchangeable Na⁺ by H⁺. So solot soils may have acid reaction in the upper portion of a profile.

2 ESP = exchangeable sodium percent =

3 A treatment of the graph given in this textbook by L.R.Petrenko allowed to derive the equation:

L.R., m = h_(cm) · [3-ln (12.5- )], were L.R. is leaching rate in meters, h – is the depth of saline soil layer due to be leached; C₁- the actual solt concentration in this layer, and C₂-the “desirable” salt concentration in the same layer.