Nguyễn Trung Hiếu * , Trần Kim Tính Võ Công Thành

* Tác giả liên hệ (nguyentrunghieu_toasoanctu@gmail.com)

Abstract

This study was carried out at Hong Dan district - Bac Lieu province. Soil samples were taken at 5 different areas where salinity levels changes occurs in different time of a year. The time chosen to take sample was in April (high salinity) and in October (lower salinity). There were 70 soil samples collected. Water samples were also collected. Results showed that, Mg concentration in both soil and water was higher than Ca concentration. The concentrations of Ca in soil and water were controlled by gypsium, with log(Ca2+)=-2.3. All samples taken in April had very high salt content, the SAR and the ESP were higher than the warning level (SAR should be < 15). In October, salt in water was decreased due to rain and the SAR decreed accordingly, but ESP decreased in some places, but still high in the others. The relationship between SAR and ESP was not stable established as proposed by Gapon (1933) with KG # 0.5. Calculated data showed that an amount of rainfall of 750 mm to reduce ESP to below 15 was really needed.
Keywords: Soil salinity, SAR, ESP, Gabon, salt tolerant rice

Tóm tắt

Đề tài “Đặc tính hóa học đất mặn trồng lúa sỏi vùng Hồng Dân – Bạc Liêu” được đặt ra nhằm tìm hiểu đặc tính hóa học, đề xuất cách theo dõi tình trạng mặn để canh tác lúa. Mẫu đất lấy ở 5 vị trí có thời gian mặn khác nhau trong năm, tháng 4 (mặn cao) và tháng 10 (đã có mưa nhiều). Tất cả có 70 mẫu đất được lấy. Mẫu nước ở các điểm trên cũng được lấy. Kết quả cho thấy rằng, lượng Mg trong mẫu đất cũng như trong mẫu nước đều cao hơn Ca. Trong nước mặn, nồng độ Ca hiện diện theo cân bằng của gypsium, với log (Ca2+) = -2,3. Tất cả các mẫu đất lấy vào tháng 4, có hàm lượng muối rất cao, hai chỉ số SAR và ESP đều vượt ngưỡng cho phép (SAR<20 và ESP< 15). Đến tháng 10, nồng độ muối trong nước giảm, SAR giảm dưới ngưỡng cho phép, nhưng ESP có mẫu dưới 15, nhưng có mẫu cao hơn. Mối quan hệ giữa SAR và ESP của đất không thành lập một cách ổn định theo phương trình được đề nghị của Gapon (1933) với KG #0,5, mà luôn thay đổi theo sự thay đổi độ mặn trong hệ thống đất-nước. Lượng mưa cần 750 mm mới có thể làm giảm ESP xuống dưới 15.  
Từ khóa: Đất mặn, SAR, ESP, Gapon, lúa chịu mặn

Article Details

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