High‐frequency Irrigation for Water Nutrient Management in Humid Regions

Abstract

A water‐nutrient management method was designed to prevent plant‐water and nutrient stresses while maximizing the available soil water storage to accommodate rainfall. This method minimized the need for the soil as a storage reservoir for water and nutrients by frequently irrigating a portion of the root zone with small amounts of water and nutrients. The optimal range of soil matric potential, based on soil oxygen diffusion rate, soil strength, water desorption characteristics, and unsaturated hydraulic conductivity was used to determine high‐frequency irrigation criteria for sweet corn (Zea mays L.). Trickle‐irrigated plots yielded 12 and 14% more corn than did the furrow‐ and sprinkler‐irrigated plots. When fertilizers were broadcast and banded, soil NO3‐N profiles measured near the end of the growing season showed that, compared to furrow and sprinkler irrigation, trickle irrigation reduced NO3‐N losses from the root zone.Optimal ear yield was produced with high‐frequency trickle irrigation when the soil matric potential at the 15‐cm soil depth was controlled at about −0.2 bar and plants were fertilized with 168 kg/ha each of N and K. Ear yield for this treatment was 66% higher than that for nonirrigated corn fertilized at the same rate. Soil NO3‐N did not accumulate in the profile with depth and time in plots fertilized at the 168‐kg/ha rate, but did accumulate in plots fertilized with 336 kg/ha. Generally, plots trickle‐irrigated with fertilizer solution had a higher soil NO3‐N content on the row than 50 cm from the row.The results of this research indicate that water use efficiency, N‐use efficiency, and N leaching can be controlled in sandy soils when N and K are applied with high‐frequency trickle irrigation systems and N and K rates are adjusted to maintain an optimal N‐level in corn plants.

Micro-Irrigation Systems and Fertigation

“…The application of chemicals through the irrigation system became a common practice in modem irrigated agriculture (Bresler 1977, Elfving 1982, Hairstone et al 1981, Phene and Beale 1976, Papadopoulos 1986b1987a;.…”

“…Some potential advantages of fertigation are: improved efficiency of fertilizer recovery (Miller et al 1981, Phene andBeale 1976), minimal fertilizer losses due to leaching (Bresler 1977, Klein et al 1989, Papadopoulos 1985, Stark et al 1983, control of nutrient concentration in soil solution (Bar-Yosef 1977, Papadopoulos 1986 andb;1987b), control of nutrients form and ratio of the various forms particularly for Nfertilizers and flexibility in timing of fertilizer application in relation to crop demand based on development and physiological stage of crops (Bresler 1977). Advantages of scheduling fertilizer applications on the basis of needs are potentially reduced nutrientelement losses associated with conventional application methods that depend on the soil as a reservoir for nutrients.…”

Caracterização do intervalo hídrico ótimo de um latossolo roxo sob plantio direto

“…Em um solo compactado, Boone et al (1987) demonstraram que a ocorrência de restrições ao crescimento das plantas por excessiva resistência e, ou, reduzida difusão de oxigênio no solo foi dependente da variabilidade temporal da umidade devida à distribuição da precipitação. A variação do conteúdo de água no solo foi utilizada por Phene & Beale (1976) para demonstrar ser possível obter condições de abundante desenvolvimento de raízes num solo compactado.…”

Compactação do solo no crescimento radicular e produtividade da cultura do milho

“…Boone et al (1987) demonstraram que em solo compactado, com alta resistência ou reduzida difusão de O 2 , a restrição ao crescimento das plantas dependeu da distribuição pluviométrica, ou seja, das condições de umidade do solo. A variação do conteúdo de água no solo também foi utilizada por Phebe & Beale (1976) para demonstrar ser possível obter condições de abundante crescimento de raízes num solo compactado.…”