Aspects of formation of soil water regime and water consumption of corn under subsurface drip irrigation

The results of experimental researches on studying of features of formation of a water mode of soils, water consumption processes, and corn yield under different schemes of irrigation pipelines (IP) under subsurface drip irrigation (SDI) in the Steppe of Ukraine. The wetting zone of dark-chestnut residual-saline sandy soil (SI "SF "Brylivske") changed. There is a shift of the center relative to the drip water outlet into deeper horizons of the soil profile (up to 52 cm) with the increasing norm; soil layer 0-15 cm is almost not moistened, regardless of watering rate. At a distance of IP 1,0 m closing of wetting zones, occur at irrigation rates of 2,7 m3/100 running meter (r. m), and at a distance of IP 1,4 m does not occur even at irrigation rates of 3,7 m3/100 r. m, while the depth of wetting reaches 90 cm. The wetting zone of chernozem sandy loam on the loess species (SI "SF "Velyki Klyny") with irrigation rates of 2,7 m3/100 r. m was observed on the soil surface. The maximum depth of wetting, with irrigation norms of 3,7 m3/100 r. m, reached 70 cm with a maximum diameter of 79 cm at a depth of 25 cm. Closing of wetting zones was not observed. Studies at SI "SF "Brylivske" have confirmed that the depth of IP placement (on the soil surface or at a depth of 30 cm) influenced the formation of the soil water regime and the corn yield. The minimum total water consumption was 6271 m3/ha under drip irrigation (DI) (IP 1,4 m), 17 % more than SDI (IP 1,4 m), and 29% more than SDI (IP 1,0 m). The highest yield was obtained in the case of DI (IP 1,4 m) of 15,72 t/ha. SDI (IP 1,0 m) received 13,93 t/ha, and SDI (IP 1,4 m) received 13,50 t/ha. The distance between the IP in 1,0 m and 1.4 m of the SDI system did not significantly affect corn yield (13.93 and 13.50 t/ha, respectively), but at a distance of IP 1.4 m, the water consumption ratio was 6.8% less compared to IP 1,0 m. The value of the irrigation rate in the variants SDI (IP 1.0 m) was higher than SDI (IP 1,4 m) by 13,6 %. Therefore, in terms of irrigation water consumption and capital expenditures, the SDI (IP 1,4 m) is more economical. Experimental studies conducted in the SI "SF "Velyki Klyny" show that the depth of placement of IP (on the soil surface or at a depth of 20 cm) did not affect the corn yield. For DI (IP 1,0 m) the yield was 12,00 t/ha and for SDI (IP 1.0 m) was 12,10 t/ha, with a water consumption ratio of 533,8 m3/t, and for DI (IP 1,0 m) by 3,6 % more. The research results confirm the importance of the parameters of SDI system for the formation of soil water regime and, accordingly, the realization of the potential of varieties and hybrids of crops for their cultivation by SDI.

INFLUENCE OF OPERATIONAL MODES OF SOWING UNITS ON SOWING QUALITY, SOIL WATER REGIME AND SPRING WHEAT YIELD

One of the promising directions for the development of crop production under present-day conditions is the im-provement of agricultural technologies of crop cultivation. Sowing is the most important technological operation; its quality largely determines the achievement of high yields. In this regard, the type of the seeding working body and the operating modes ofthe machine-tractor unitssignificantly affect the energy and agrotechnical characteristics of the sowing. As a result, it becomes necessary to substantiate the zonal parameters and operating modes of the sowing units taking into account the agronomic, technical and eco-nomic indices. The experiment was carried out on the farm of the OOO KKh “Zaytsev” in the Tyumentsevskiy District of the Altai Region. Based on the implementation of the field experiment using the planning of the experiment, a quantitative assessment of the effect of the speed opera-tional modes of the John Deere 730 and John Deere 1890 seeding units on the quality of spring wheat sowing, soil water regime and the yield was obtained. Each unit operat-ed at 4 levels of travel speeds. As a result, a technical and economic assessment of the compared sowing options was given. The results obtained will serve as the basis for substantiating the parameters and operating modes of the sowing units under operating conditions.

EFFECTS OF CONTROLLED DRAINAGE ON SOIL WATER REGIME AND QUALITY IN LITHUANIA

Lithuania remains one of the most extensively drained of the Baltic and Nordiccountries. The overall drained area (ditches plus tile drains) totalled 87% of theagricultural land area. Many nutrients from soil are leached through drainageresulting in polluting streams (drain flow receivers) water. Drain flow is treated asa major determinant of water quality. Therefore, the reduction of nutrients enteringthe drains is very important. Controlled drainage conception, when the outflowheight is increased at the mouth, helps reduce drainage runoff and partially purifywater. The aim of the research was to establish controlled drainage influence on thesoil moisture regime, nitrogen and phosphorus leaching. Investigations werecarried out in sandy loam and loam soils in the Middle Lithuanian Lowland. Basedon studies, several tendencies were observed: when drainage outflow began, theamount of soil moisture in subsoil (50-80 cm layer of the soil) of controlleddrainage plot was higher than in the conventional drainage plot, and highermoisture supplies stayed for a longer period of time. Controlled drainage had nodirect impact on phosphorus and nitrogen concentrations but they were influencedby the leaching quantities of plant usable nutrients. The reason that in many caseslower nitrate nitrogen (54% of all measurements) and phosphorus concentrations(77% of all measurements) were found in the conventional system rather than inthe controlled drainage might be connected to the fact that the latter area containedpredominantly lighter textured soils (sandy loam) making it easier to wash awaythe nutrients unused by plant.