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.

IRRIGAÇÃO POR GOTEJAMENTO SUBSUPERFICIAL EM CULTIVARES DE CANA-DE-AÇÚCAR IMPACTAM A AGREGAÇÃO DO SOLO?

IRRIGAÇÃO POR GOTEJAMENTO SUBSUPERFICIAL EM CULTIVARES DE CANA-DE-AÇÚCAR IMPACTAM A AGREGAÇÃO DO SOLO? YASMIN REIS MAGALHÃES1; ANDERSON PRATES COELHO2; CAROLINA FERNANDES1; ALEXANDRE BARCELLOS DALRI2 1 Departamento de Ciências da Produção Agrícola, Universidade Estadual Paulista (Unesp), Faculdade de Ciências Agrárias e Veterinárias, Via de Acesso Professor Paulo Donato Castellane, s/n Km 5, 14884-900, Jaboticabal, São Paulo, Brasil. [email protected]; [email protected] 2 Departamento de Engenharia e Ciências Exatas, Universidade Estadual Paulista (Unesp), Faculdade de Ciências Agrárias e Veterinárias, Via de Acesso Professor Paulo Donato Castellane, s/n Km 5, 14884-900, Jaboticabal, São Paulo, Brasil. [email protected]; [email protected] 1 RESUMO Objetivou-se avaliar o efeito da irrigação por gotejamento subsuperficial em cultivares de cana-de-açúcar, contrastantes na responsividade à irrigação, na agregação de Latossolo argiloso. O experimento foi realizado em Latossolo Vermelho eutroférrico, de textura argilosa (587 g kg-1 de argila). Foram coletadas amostras deformadas de solo em vinte pontos em cada uma das quatro áreas de cana-de-açúcar avaliadas nas camadas 0,00-0,10 m e 0,10-0,20 m. As áreas correspondiam ao cultivo irrigado e não irrigado, das cultivares CTC 4 e IACSP93-3046. Foram determinados e calculados o índice de estabilidade dos agregados, diâmetro médio ponderado de agregados, fracionamento físico do carbono orgânico e as classes de agregados. Os dados foram submetidos à estatística descritiva e multivariada de fatores. De acordo com as correlações das variáveis, a agregação do solo foi dividida em dois processos, sendo o primeiro denominado de “Dimensão de agregados” e o segundo “Estabilidade de agregados”. Observou-se que a irrigação por gotejamento subsuperficial promove maior “Estabilidade de agregados” do solo em áreas cultivadas com cana-de-açúcar. Além disso, cultivares de cana-de-açúcar proporcionam diferenças na agregação do solo, sendo que a cultivar responsiva à irrigação IACSP93-3046 promove maior “Dimensão de agregados” do solo em relação a cultivar não responsiva CTC 4. Palavras-chave: diâmetro médio ponderado de agregados, estabilidade de agregados, carbono orgânico, Latossolo. MAGALHÃES, Y. R.; COELHO, A. P.; FERNANDES, C.; DALRI, A. B. DOES SUBSURFACE DRIP IRRIGATION IN SUGARCANE CULTIVARS IMPACT SOIL AGGREGATION? 2 ABSTRACT The aim was to evaluate the effect of subsurface drip irrigation with sugarcane cultivars, contrasting in the responsiveness to irrigation, in the aggregation of Oxisol clayey. The experiment was conducted in a clayey Oxisol (587g kg-1 of clay). Deformed soil samples were collected at twenty points in each four areas of sugarcane evaluated in the layers 0.00-0.10 m and 0.10-0.20 m. The areas corresponded to the irrigated and non-irrigated cultivation of cultivars CTC 4 and IACSP93-3046. The aggregate stability index, weighted average diameter of aggregates, physical fractionation of organic carbon and aggregate classes were determined and calculated. The data were submitted to the descriptive and multivariate factor statistics. According to the correlations of the variables, soil aggregation was divided into two processes, the first being called “Aggregates dimension” and the second “Aggregates stability.” It was observed that subsurface drip irrigation promotes greater soil “Aggregate stability” in areas cultivated with sugarcane. Additionally, sugarcane cultivars provide differences in soil aggregation, and the cultivar responsive to irrigation IACSP93-3046 promotes a larger soil “Aggregates dimension” than the non-responsive cultivar CTC 4. Keywords: weighted average diameter of aggregates, aggregate stability, organic carbon, Oxisol.

Irrigation Regime for Protection on Root Intrusion for Subsurface Drip Irrigation

Root intrusion into emitters poses a threat to the service lives of subsurface drip irrigation systems. In an attempt to address this problem, an experiment was conducted on spring wheat grown in soil columns installed in a greenhouse to study the effects of irrigation regimes in protecting against root intrusion into emitters. Spring wheat was planted in soil columns. The specifications of the soil column were 15-cm width, 60-cm length and 100-cm depth. Drip tapes were buried manually in the center of the soil columns at a -40-cm depth. The soil matrix potential at a 20-cm depth immediately over the drip emitters was used to schedule the subsurface drip irrigation regime. Five different irrigation arrangements, with targeted soil matrix potentials of -10, -20, -30, -40 and -50 kPa, were maintained. The soil matrix potential influenced the spring wheat root distribution, emitter flow rate, root intrusion, and spring wheat yield and quality. The total root dry weight increased as the soil matrix potential decreased. Root length density at 35-45-cm increased as the soil matrix potential increased. The decrease in the emitter flow rate increased along with the soil matrix potential. All the treatments had root intrusion, but its severity was correlated with the soil matrix potential. Root intrusion first decreased as the soil matrix potential decreased but then increased as the soil matrix potential continued to decrease. The lowest root intrusion rate (22.22%), as well as the greatest relative yield and relative thousand-grain weight values, were achieved with a soil matrix potential of -40 kPa.