كليدواژه :
كارايي زراعي نيتروژن , بهرهوري ناخالص نيتروژن , عوامل خاكي , كربن آلي خاك , كارايي فيزيولوژيك نيتروژن
چكيده فارسي :
كارايي مصرف نيتروژن شاخص بسيار مهمي براي قضاوت در مورد استفاده آگاهانه نيتروژن در گياهان به شمار مي‌رود. اين شاخص تحت تأثير عوامل مديريتي، اقليم و همچنين ويژگيهاي خاك قرار دارد. به منظور تخمين كارايي مصرف نيتروژن در مقياس مزرعه‌اي و تعيين نقش عوامل خاكي، تعداد 20 مزرعه گندم در نقاط مختلف استان خراسان رضوي انتخاب گرديد. دو سطح كودي نيتروژن صفر و برابر با عرف زارع از منبع اوره در هر يك از مزارع اعمال گرديد. در مزارع آزمايشي عملكرد دانه گندم (عرف زارع) پس از ثبت به دوگروه جامعه با عملكرد بالا (بيش از 5 تن در هكتار) و جامعه با عملكرد پايين (كمتر از 5 تن در هكتار) تقسيم شدند. سپس شاخص‌هاي كارايي نيتروژن در هر دو گروه جامعه تعيين گرديد. نتايج نشان داد شاخص‌هاي كارايي نيتروژن در هر دو گروه جامعه عملكردي بسيار كمتر از حد مطلوب بود. باوجود اين، در جامعه عملكرد بالا، كارايي زراعي (2/8 كيلوگرم در كيلوگرم)، كارايي بازيابي ظاهري (25 درصد) و بهرهوري ناخالص (46 كيلوگرم در كيلوگرم) بيش از جامعه عملكرد پايين بود، اما تفاوتي بين كارايي فيزيولوژيك در دو جامعه عملكردي وجود نداشت. بر خلاف جامعه عملكرد بالا، در گروه جامعه عملكرد پايين همبستگي معنيداري بين كارايي زراعي نيتروژن و كربن آلي خاك (P
چكيده لاتين :
Nitrogen use efficiency (NUE) is a critically important indicator for judging the wise use of N fertilizer in crops. It can be affected by management factors or soil properties. This study was conducted to estimate NUE in wheat based on large scale fields (20 wheat farms) trials and determining the role of soil factors, in Khorasan Razavi province. Two levels of N as urea (0 and conventional) were applied in each of the fields. In the fields, grain yield (conventional) was divided into low yield population (LYP, GY< 5 Mg ha-1) and high yield population (HYP, GY ≥ 5 Mg ha-1) categories. Then, apparent recovery efficiency (ARE), physiological efficiency (PE), agronomic efficiency (AE) and Partial Factor Productivity (PFP) were calculated for N in both yield populations. The results showed that nitrogen efficiency indices in both yield populations were much lower than optimum level. However, AE (8.2 kg/kg), ARE (25%), and PFP (46 kg /kg) in the HYP were more than in the LYP, but there was no difference between PE in both yield populations. There was a significant correlation between AE and soil organic carbon (r = -0.97, P <0.01, also ARE with soil organic carbon (r = -0.82, P<0.05) and soil clay content (r = 0.68, P <0.05) for LYP in contrast to the HYP). While PFP exhibited positive correlation with soil organic carbon (r = 0.86, P <0.01) and negative correlation with soil electrical conductivity (r = -0.77, P <0.05) for LYP, this relationship was weaker with soil organic carbon in HYP. None of soil factors had a significant effect on PE. These results show that soil factors such as organic carbon, salinity, and clay content of soil had a decisive role in AE, ARE, and PFP in the LYP. In contrast, soil factors had no effect on nitrogen efficiency indices in the HYP (with the exception of the effect of soil organic carbon on PFP).
