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Publication Date

1981

Description

The shortage of irrigation water in the semiarid zone of Israel necessitates the use of partially treated municipal effiuents for irrigation of forage grasses. Irrigation with sewage effiuents is being considered very carefully with the aim of maximizing pro­duction and minimizing the pollution ha.zarc;l. A high nitrogen (N) input originating from intensive application of effiuent water may well increase dry-matter production, but it also increases t,he pollution hazard. Frequent application of relatively small quantities of effiuent water was suggested as an efficient method of improving N uptake by rhodesgrass ( Chloris gayana Kunth.) swards. It was expected that nitrate pollution would be reduced and nitrogen fertilizer could be saved. In fie\d experiments rhodesgrass was sprinkle-irrigated at different frequencies with three sources of water in combination with four lev«;ls of N fertilization. Irrigation ai;cording to 100% class A pan evaporation (approximately 1,000 mm) revealed the superiority of twice-a-week ap­plication of effiuents on fine soil. This schedule resulted in high yields and high N recovery as well as no response to additional N fc;rtilization. Differences between irrigation frequencies diminished as N input increased, and effiuent application was reduced to 80% of class A pan evaporation. Total N input higher than 660 and 380 kg/ha did not increase dry-matter production on fine anc;I sand dune soils, respectively, but did increase N losses. Dry-matter production and N-balance values are discussed in rela­tion to quantity and frequency of water applic􀁋tion and N loss due to denitrification or leaching.

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Waste- Water Application, Dry-Matter Production, and Nitrogen Balanced Rhodesgrass Grown on Fine-Textured Soil or on Sand Dunes

The shortage of irrigation water in the semiarid zone of Israel necessitates the use of partially treated municipal effiuents for irrigation of forage grasses. Irrigation with sewage effiuents is being considered very carefully with the aim of maximizing pro­duction and minimizing the pollution ha.zarc;l. A high nitrogen (N) input originating from intensive application of effiuent water may well increase dry-matter production, but it also increases t,he pollution hazard. Frequent application of relatively small quantities of effiuent water was suggested as an efficient method of improving N uptake by rhodesgrass ( Chloris gayana Kunth.) swards. It was expected that nitrate pollution would be reduced and nitrogen fertilizer could be saved. In fie\d experiments rhodesgrass was sprinkle-irrigated at different frequencies with three sources of water in combination with four lev«;ls of N fertilization. Irrigation ai;cording to 100% class A pan evaporation (approximately 1,000 mm) revealed the superiority of twice-a-week ap­plication of effiuents on fine soil. This schedule resulted in high yields and high N recovery as well as no response to additional N fc;rtilization. Differences between irrigation frequencies diminished as N input increased, and effiuent application was reduced to 80% of class A pan evaporation. Total N input higher than 660 and 380 kg/ha did not increase dry-matter production on fine anc;I sand dune soils, respectively, but did increase N losses. Dry-matter production and N-balance values are discussed in rela­tion to quantity and frequency of water applic􀁋tion and N loss due to denitrification or leaching.