Land suitability assessment for second cropping in terms of low temperature stresses using landsat TIRS sensor

Abstract

The second cropping which is done in the autumn after the main cultivation is one of the ways to increase food security, farmers' income, and thus prevent migration of villagers. The main limiting factor in autumn cultivation is the reduction in ambient and soil temperatures, which causes a severe drop in crop yield if it reaches below the physiological base temperature and freezing temperature. In Gilan, one of the northern provinces of Iran more than 90 % of agricultural land is cultivated once a year and has no production in half of the year. Accordingly, the purpose of the present study is to evaluate the feasibility of autumn cultivation of rice and hull-less seed pumpkin (Cucurbita pepo L. var. pepo subsp. styriaca) in terms low temperature stresses. In the first step, the land use map was prepared using the fusion of images with panchromatic band of Landsat 8 Maximum Likelihood classification method and then agricultural lands were separated. The land surface temperature (LST) maps were extracted on two dates, October 30, 2018 and December 17, 2019 using the TIRS sensor. Comparison of the estimated data with the meteorological data showed that LST was 0.6 °C higher than the meteorological data on October and it was 1.1 °C lower on December. Then, the LST map was validated with meteorological data in the last 10 years and a modified map was obtained to measure the cultivation potential of rice and hull-less seed pumpkin. Comparison of LST maps obtained on the two dates showed that the temperature variation was greater in the colder date. Considering base temperatures of 12 and 10 °C for rice and pumpkin, respectively, as well as the freezing temperature of 5 °C for these two crops, land suitability was identified. Having the minimum temperature of 15 °C for almost all lands, there will be no temperature stress for the crops until October 30. But, if the crop calendar lasts until December 17, only 2.62 % of agricultural lands have the potential to cultivate rice without temperature restrictions. Meanwhile, lands with cultivation potential for pumpkin were estimated 6983.3 ha (83.5 %) on December. Therefore, pumpkin cultivation has a lower temperature risk compared to rice in Rezvanshahr. The results of this study, in addition to being the required source for any planning in the field of autumn cultivation of rice and pumpkin, is one of the main sources for selecting different crops of the second cropping and their crop calendar.