Distribution of Nutrients in the Soils of a Unique Tropical Agroecosystem

Abstract

Kuttanad agroecosystem, once the rice bowl of Kerala, is facing a serious threat from human activities. The present study assessed the nutrient status of Kuttanad paddy soils and the spatial distribution of Nutrients using GIS technique. 117 soil samples were collected from the six agroecological zones of Kuttanad. Out of the 117, 92 were from paddy fields and 25 were from canals. The soil samples were analyzed for pH, organic Carbon (%), available nitrogen (kg/ha), available phosphorous (kg/ha) and available potassium (kg/ha). The spatial distribution of nutrients showed that high available nitrogen content was observed at various parts of the Kuttanad agroecosystem except Vaikom Kari, northern part of North Kuttanad and western part of Kayal Lands. A cluster of area including southeast region of Lower Kuttanad, northern part of Purakkad Kari and north east regions of Upper Kuttanad as well as north east part of Vaikom Kari has showed the highest concentration of phosphorous. High intensity of potassium was observed in the central portion of Kayal Lands, North Kuttanad, northeast and southeast regions of Purakkad Kari and Lower Kuttanad respectively. It can conclude that monsoon flooding has a major role in the regulation of nutrients in the Kuttanad paddy fields. N and P are taken away from the soil by the inundated water whereas potassium is deposited in these areas. The high concentration of nutrients observed at the sites which are having more than one time cultivation and also watering and dewatering has a significant role in regulating the nutrient status of the Kuttanad agricultural wetland ecosystem.

Fluoride contamination in wetlands of Kuttanad, India: Predisposing edaphic factors

“…Despite this, the soils showed an available N content ranging from 275.70-502.95 kg h -1 which remained below the higher N availability class (>560 kg h -1 ). This contrasts the finding of Thafna et al (2017) who observed a high N content (771.91 kg h -1 ) in Kuttnad soils. This is possibly due to an increased utilization of N by the previous crop (Guo et al, 2017).…”

“…The available K content of the soils ranged from 46.50-383.20 kg h -1 which is in agreement with the earlier finding of Thafna et al (2017) that the soils in this region had a high content of K. The increase in soil organic matter (Thafna et al, 2017), soil texture and irrigation regime are some of the reasons reported for the increase in K content in soil.…”

“…It is an established fact that the rice crop utilizes only 25-30% of applied P. and the remaining part which is not readily available remain in soil (Gudadhe et al, 2015) which gradually increase as available P over a period of time. The available K content of the soils ranged from 46.50-383.20 kg h -1 which is in agreement with the earlier finding of Thafna et al (2017) that the soils in this region had a high content of K. The increase in soil organic matter (Thafna et al, 2017), soil texture and irrigation regime are some of the reasons reported for the increase in K content in soil.…”

“…The increase of clay fraction in the soil is reported to influence the CEC of soil (Khaledian et al, 2017). Soils in general had a high OC (>7.5 g kg -1 ) ranging from 12-36.80 g kg -1 with a mean value of 23.40 g kg -1 which was reported in other studies (Thafna et al, 2017). The presence of sand layers, differential accumulation of organic matter and sedimentary nature of the parent materials are attributed to be the reason for heterogeneity in OC distribution (Thampatti and Jose, 2000).…”

Total Nitrogen Estimation of Paddy Soil Using Visible and Near Infrared Spectroscopy

“…Adv Agri Food Res J 2021; 2(2): a0000232. https://doi.org/10.36877/aafrj.a0000232 areas and less fertiliser application in low nutrient field zones (Thafna et al, 2017;Whetton et al, 2017). This uniform fertiliser management under spatially variable conditions can cause crop nutrient deficiencies as well as increases the in input cost due to over fertiliser application.…”