اثر آبیاری جویچه‌ای یک در میان ثابت و متغیر بر تغییرات شوری، فسفر و پتاسیم خاک در اراضی زیرکشت نیشکر

بهبود روش های آبیاری راهکار مناسبی جهت افزایش کارآیی مصرف آب در مزارع و در نتیجه کاهش بحران آب در مناطق خشک و نیمه خشک می باشد. با توجه به مصرف بالای آب در مزارع نیشکر و همچنین کمبود و افت کیفیت آب رودخانه ها، این پژوهش در دانشگاه علوم کشاورزی و منابع طبیعی خوزستان، جهت بررسی تاثیر روش های آبیاری کامل (مرسوم)، آبیاری جویچه ای یک در میان ثابت و متغیر بر توزیع شوری و غلظت عناصر فسفر و پتاسیم در خاک سطحی کف، میانه و بالای پشته در ابتدا، وسط و انتهای جویچه، در مزرعه کشت نیشکر میان آب شوش، با تعداد 243 نمونه در سه تکرار به صورت فاکتوریل در قالب طرح کاملاً تصادفی انجام شد. نتایج نشان داد کمترین متوسط میزان شوری تحت تاثیر روش کم آبیاری جویچه ای یک در میان ثابت به میزان 1.92 دسی زیمنس بر متر گزارش شد. از نظر تغییرات مکانی، کمترین میزان شوری در کف و ابتدای جویچه ها مشاهده شد. تغییر روش آبیاری از مرسوم به یک در میان ثابت باعث کاهش معنی دار میزان فسفر قابل جذب گردید. بیشترین مقدار فسفر در قسمت میانی پشته ها به میزان 8.47 میلیگرم در کیلوگرم گزارش شد. تغییرات پتاسیم خاک مستقیماً تحت تاثیر روش آبیاری قرار نگرفت؛ اگرچه، بیشترین مقدار آن در کف جویچه ها مشاهده شد. با توجه به برتری روش های کم آبیاری در ارتباط با ویژگی های مورد بررسی، استفاده از این روش ها به ویژه روش آبیاری جویچه ای یک در میان ثابت، به جای روش آبیاری مرسوم، توصیه می گردد. از نظر مکان کاشت، با توجه به مقادیر شوری و غلظت عناصر فسفر و پتاسیم، کف و میانه پشته مناسب تر بوده و پیشنهاد می گردد.

effect of variable and fixed alternate furrow irrigation on salinity, phosphorous and potassium concentration in soil of sugarcane field

introduction the highest amount of water consumption is allocated to the agricultural sector, which has led to a water crisis due to increasing demand for food production and non-conservative agriculture and climate change in some countries. sugarcane needs a lot of water during the growing season and is sensitive to drought. under drought conditions and water stress, the intensity of reverse flow of water to the soil surface increases and can cause salinization of the soil around the roots of sugarcane, which is a relatively sensitive plant related to salinity. due to the high-water consumption in sugarcane fields and also the shortage and decline of water quality in dry years, this study aimed to investigate the effect of conventional and deficit irrigation by variable and fixed alternate furrow irrigation on soil salinity and some nutrient concentration consist of phosphorous and potassium in sugarcane field. materials and methods to investigate the effect of irrigation methods on salinity distribution and concentration of phosphorous and potassium in soil, this experiment was conducted with independent variables of irrigation method treatment including conventional (complete) irrigation, variable alternate furrow irrigation and fixed alternate furrow irrigation, irrigation round treatment including before irrigation, after one and two times irrigation, sampling location treatment including bottom, middle and top of raised bed and sampling position treatment consist of start, middle and end of furrow. the experiment was performed factorially in a completely randomized design with three replications in sugarcane fields of mianab in susa. statistical analysis was performed using spss software and mean comparisons were performed by duncan's multiple range test. charts were drawn using excel software. results and discussion the results showed that irrigation method is mainly affects salinity distribution and concentration of phosphorus in soil. the fixed alternate furrow irrigation method had the greatest effect on soil salinity changes and reduced the salinity as compared to the conventional method and the variable alternate furrow irrigation. in general, in the conventional irrigation method (complete irrigation of all furrows) and variable alternate furrow irrigation, there is no constantly dry furrow as compared to the fixed alternate furrow irrigation method, and this intensifies the accumulation of salts on the sides and the top of raise beds. increasing the frequency of irrigation (irrigation round) reduces the soil salinity so that in soil samples before irrigation, soil salinity was 2.30 ds/m and with one round irrigation, this amount decreased by 7.8% to 2.12 ds/m and with two rounds of irrigation reached to 2.09 ds/m. in terms of locative variation of salinity related to the fixed alternate furrow irrigation method, the lowest amount of salinity was observed in the bottom of the raised bed. with increasing distance from the beginning of furrow, an upward trend in soil salinity was reported. regarding the change in the amount of available phosphorus in the soil under the influence of irrigation method, any of the deficit irrigation methods can be used as an