ECOLOGICALLY SAFE GROWING TECHNOLOGIES FOR SPRING BARLEY ON ORGANIC FARMING

Field trials were carried out on organic farming fields at the Research Institute of Agriculture of the Latvia University of Agriculture (LUA). The content of nitrates in soil, the influence of previous plants (red clover, winter rue, bare fallow, fallow and green manure), use of stable manure (60 t ha-1 or without) and harrowing (without harrowing, before shooting, at the stage of clustering, before shooting and at the stage of clustering) on the yield and weediness of spring barley „Sencis” were tested during 2003-2004. The content of nitrates in soil was 8-79 mg kg-1. Previous plants and stable manure influenced barley grain yields. Harrowing increased the yields of barley only after winter rye for green manure by using stable manure, but the time of harrowing had no influence on the yield of barley. The quality of grain was satisfactory. 1000 thousand weight was medium – 33.5–38.4 g, medium was also volume weight – 609.0–633.5 g. The content of total protein was satisfactory to good – 9.6 – 11.7 %

INFLUENCE OF FERTILIZERS AND LIMING ON THE AGROCHEMICAL PARAMETERS OF SOIL AND LOSSES OF PLANT NUTRIENTS THROUGH DRAIN WATER

The aim of the research was to study the influence of mineral fertilizers and liming on yields of field crops and agrochemical parameters of soil and loss of plant nutrients through drain water. Since 1982, long-term field trials were carried out under crop succession with long-term grass, grain (rye, triticale, spring wheat, barley, oat), potatoes and rape. Annually from soil thought drains were leached about 3.0 - 21.9 kg ha-1 nitrogen, 0.1 - 0.5 kg ha'1 and 0.6 -1.7 kg ha-1 potassium. Application of P0 and P30 led to the further decrease of phosphorus content as fa r as 0-6 mg kg especially in limed soil. Significant increase of phosphorus content was observed only using phosphorus rate P90. Positive NPK balance in limed trial plots was achieved with annual inputs of 90 kg ha-1 N, 100 kg ha-1 P20 s and 90 Kg ha-1 K20

THE CHANGES OF PHOSPHORUS AND POTASSIUM IN SOIL UNDER DIFFERENT LIME RATES

The paper describes the influence of liming to phosphorus and potassium accumulation in soil. The research has been carried out at the Institute of Agronomy of Latvia University of Agriculture in the long-term subsurface drainage field established in Skrīveri in 1981. The experimental field was established with four rates of mineral fertilizers: without fertilizers (F0), N45P30K45 (F1); N90P60K90 (F2), N135P90K135 (F3) and four rates of lime: without liming (L0), 2.58 (L1), 5.70 (L2), 11.40 (L3) t ha-1 CaCO3. Primary liming was done in 1981 (Estonian oil shale ashes), the maintenance liming was performed in 1994 (dolomitic limestone) and 2014 (BALTKALK). After 35 years of trial similar soil parameters showed significantly different content of phosphorus and potassium related to the different rates of liming in all fertilizing levels. Without fertilizers, the liming provided the increase of phosphorus content in soil from 14 to 36 mg kg-1, but the increase of potassium – from 55 to 72 mg kg-1. On a low background of fertilizers (N45P30K45) the content of phosphorus and potassium under liming increased respectively from 20 to 32 mg kg-1 for phosphorus and 75 to 96 mg kg-1 for potassium. At the fertilizers level N90P60K90 the content of phosphorus and potassium increased respectively from 94 to 81 mg kg-1 for phosphorus and 115 to 165 mg kg-1 for potassium. At the fertilizers level N135P90K135 the content of phosphorus and potassium increased respectively from 174 to 203 mg kg-1 for phosphorus and 166 to 214 mg kg-1 for potassium

Use of Lignosilicon to Improve the Harvest and Quality Parameters Of Potato

Lignosilicon (LSi), a plant growth activator, was synthesized at the Latvian State Institute of Wood Chemistry (LS IWC) on the basis of the wood lignocellulosic complex. It is shown that LSi, used for treatment of potato tubers before sowing at low application rates of 20-40 kg/ha, has a favourable action on the yield and quality of the tubers. In comparison with the control, the additional yield achieved on the background of LSi (20-40 kg/ha) was 18-20%. The best biochemical composition was for the tubers wetted with water and LSi-treated before the sowing, i.e., the content of dry matter and starch increased by 16% and 18%, respectively, but the content of nitrates in the tubers decreased 1.6 times. LSi can be recommended for potato cultivation under conditions of conventional and organic agriculture