اثر سيستم‌هاي خاك‌ورزي بر محتوي عناصر غذايي خاك، عملكرد و نسبت برابري زمين در كشت مخلوط چاي ترش- ماش

Effects of Tillage Systems on Changes of Soil Nutrients, Yield and Land Equivalent Ratio in Roselle – Green Gram Intercropping

به‌منظور بررسی تغییرات عناصر غذایی خاك در كشت مخلوط چای ترش و ماش آزمایشی در مزرعه آموزشی و تحقیقاتی پژوهشكده كشاورزی دانشگاه زابل در سال زراعی 93-1392، به‌صورت كرت های خردشده در قالب طرح بلوك كامل تصادفی در سه تكرار اجرا گردید. عامل اصلی 3 نوع خاك ورزی شامل بدون شخم، شخم كاهش یافته، شخم رایج (گاوآهن و دیسك) و عامل فرعی نسبت های كشت مخلوط شامل خالص چای ترش، خالص ماش،50 درصد چای ترش +50 درصد ماش، 75 درصد چای ترش+ 25 درصد ماش، 25 درصدچای ترش + 75 درصد ماش در نظر گرفته شد. صفات مورد بررسی در این تحقیق شامل (كربن آلی خاك، نیتروژن، منیزیم، كلسیم، پتاسیم، رطوبت حجمی، دمای خاك و نسبت برابری زمین) نشان داد كه سیستم بدون خاك-ورزی و تیمارهای مخلوط رطوبت حجمی بیشتری نسبت به سیستم خاك ورزی مرسوم و كشت خالص چای ترش كسب نمودند. سیستم بدون خاك ورزی و افزایش نسبت ماش در كشت مخلوط سبب افزایش میزان رطوبت و كاهش دمای خاك گردید. در بین كشت‌های مخلوط تیمار 75 درصد ماش به‌علاوه 25 درصد چای ترش بالاترین میزان كربن (99/0 درصد) و نیتروژن (087/0 درصد) را نشان داد. بالاترین مقدار نیتروژن و كربن آلی خاك پس از برداشت از برهمكنش سیستم بدون خاك‌ورزی و كشت خالص ماش به‌ترتیب 15/0 و 75/1 درصد به‌دست آمد. نتایج نشان داد كه نسبت برابری زمین در همه تیمارهای مخلوط بزرگتر از یك بود كه نشان‌دهنده برتری كشت های مخلوط نسبت به كشت خالص آن‌ها بود. بیشترین عملكرد اقتصادی چای ترش و ماش در برهمكنش سیستم بدون خاك‌ورزی و كشت خالص هر كدام به مقدار 89/990 و 20/740 كیلوگرم در هكتار به‌دست آمد. بیشترین نسبت برابری زمین از كشت مخلوط 75 درصدماش به‌علاوه 25 درصد چای ترش (36/1) به‌دست آمد. در مجموع نتایج این تحقیق اهمیت كشت مخلوط لگوم و گیاه دارویی را در استفاده بهینه از منابع محیطی، افزایش حاصلخیزی خاك و سودمندی بیشتر كشت مخلوط نسبت به كشت خالص چای ترش و ماش تأیید نمود.

<strong >Introduction </strong > Intercropping is one of the components of sustainable agriculture and as part of crop rotation in the design of sustainable system. One of the benefits of intercropping is greater use of available resources. The aims of this study were to evaluate different tillage systems and cropping patterns of Roselle and Green Gram on some soil nutrients and the use efficiency of environmental resources. Usually, intercropping used at Low fertility soil with low input conditions in the tropics region. Bahrani et al. (2007) reported that no tillage systems compared with conventional tillage with crop residue, were increased soil organic carbon content in maize production. Ramroudi et al. (2011) expressed conventional tillage reduced amount of nitrogen compared to no tillage system. <strong >Material and Methods </strong > The research was conducted at Zabol city. Split plot experiment performed based on a randomized complete block design with three replications. Main plot was three levels of tillage system (zero (without plowing), reduced (disk) and conventional tillage (disc plow)) and sub plot was planting ratio with five levels (pure culture of Roselle, pure culture of Green gram, 50% roselle+50% green gram, 25% roselle+75% green gram, 75% roselle+25% green gram) were considered. Preparing the ground in mid-June 2012, according to the type of plowing was performed. For comparison of means were used by Duncan 's test at 5% probability. <strong >Results and Discussion </strong > The effects of tillage systems, planting ratios and interaction of tillage systems × planting ratio on soil organic carbon and nitrogen were very significant. The highest and lowest levels of organic carbon were obtained in zero tillage (1.14%) and conventional tillage systems (0.63 %), respectively. The highest and lowest nitrogen of soil after harvest, of pure culture of Green gram (0.11 %) and 75 % of Roselle + 25% Green gram intercropping (0.06 %) were obtained respectively, Tillage system could not affected the amount of magnesium of soil after harvest. The comparison of means showed that the highest and the lowest magnesium content were observed in conventional tillage (17.9 ppm) and zero tillage (16.7 ppm) respectively, (Table 2). The calcium amount in a pure culture of green gram (17.9 ppm) was higher than the net cultivation of Roselle (15.5 ppm). The Most of potassium soil of intercropping 25 % Roselle +75% green gram (480.1 ppm) and the lowest amount of pure cultures of Roselle (401.8 ppm), were obtained (Table 2). Bohrani et al., (2) were reported that no tillage systems compared with conventional tillage with crop residue have increases soil organic carbon content. With the increase of Roselle in intercropping reduced soil potassium and with increase the proportion of green gram in intercropping, potassium was increased. Tillage systems, planting ratio and interactions (tillage system × planting ratio) had a significant effect on soil water content and soil temperature. Comparison of means showed that maximum and minimum soil water content of the soil related to the zero tillage (18.6 %) and conventional tillage (12.6 %). soil water content pure culture of green gram was the greater than intercropping and pure culture of Roselle. Soil temperature in pure culture of Roselle was greater than of pure culture of green gram. Effect of planting ratio was significant on LER in 1% probability level. The highest and lowest of LER was obtained in 75 %green gram + 25% (1.36) and 25 % green gram +75 % Roselle (1.15). Beheshti and Soltaniyan (2012) reported that LER in various combinations of sorghum and beans intercropping was higher than of unit. <strong >Conclusions </strong > Investigation showed that the zero tillage treatments and intercropping increased the efficiency of environmental resources and improved the soil nutrient, significantly. The highest LER was achieved 75% green gram + 25% Roselle, which is indicative of the excellence of intercropping compared to monoculture. The amount of organic carbon has shown an increase in soil fertility using zero tillage and increase percent of green gram in intercropping. The results showed that zero tillage systems, monoculture green gram and intercropping had soil water content more than conventional tillage systems and monoculture Roselle.