The critical limit of nitrogen in soil and plant (CAU R-1) was determined through a pot culture experiment with twenty five soils of Imphal West district of Manipur, India for predicting the response of rice to nitrogen application. All the soil samples were clayey in texture and acidic in reaction with the mean pH value of 5.16, electrical conductivity ranged from 0.06 to 0.14 dSm -1 with an average of 0.1 dSm -1 , organic carbon content from 1.06 to 2.62 % with mean value of 2.03%, cation exchange capacity of the soils from 12.20 to 20.20 meq/100g with mean value of 16.06 meq/100g. Available nitrogen content in soils varied from 185.00 to 331.06 kg N/ha with an average value of 267.24 kg N/ha. Available nitrogen in the soils was positively and significantly correlated with plant N content (r=0.653**), dry matter yield (r=0.556**), plant N uptake (r=0.726**) in control pots. There was also a positive and significant correlation between available N and bray's per cent yield (r = 0.519**). The critical limit of available N was established at 257 kg N/ha for soil and 1.04 % for 45 days old rice plants. Soil containing N below this critical limit may respond economically to N fertilization for growing rice.

No abstract

No abstract

Aim : Methodology :Results : Interpretation :A field experiment was conducted during winter season to study the effect of different nutrient management on growth and productivity of potato (cv. Kufri Jyoti) and soil nutrient status in new alluvial zone of West Bengal.The experimental site is located at Regional Research Station, NewAlluvial Zone of Bidhan Chandra Krishi Vishwavidalaya, Gayeshpur, Nadia, West Bengal at an altitude of 9.75m amsl. The experiment was laid out in a randomized block design with three replications and consisted of eight different treatments. Observations on growth and yield attributes were recorded and soil nutrient analysis was carried out before planting and after harvest of potato.The highest values of plant height (48.47 cm), dry matter accumulation (686.70 gm ) and crop growth rate (7.78 gm day ) was observed in the treatment (T ) receiving 100% recommended dose of fertilizer, which was statistically at par with integrated nutrient management receiving 50% RDF + 50% N as farmyard manure . Similarly, 100% RDF (T ) gave better yield parameters like dry weight of tuber (547.95 gm ), number of tubers per hill (5.57), tuber bulking rate (9.33 gm ) and maximum tuber yield of 22.19 t ha which was also statistically at par with integrated nutrient management receiving 50% RDF + 50% N as farmyard manure with tuber yield of 21.72 t ha . However, organic nutrient management containing 1/3 recommended N each from farmyard manure, vermicompost, neemcake along with rock phosphate, phosphorus solubilizing bacteria and showed significantly highest organic carbon content, total nitrogen, available phosphorus and available potassium content in soil among the various organic treatments followed by integrated nutrient management.The growth and yield attributes of potato were found to be significantly improved in the treatment receiving 100 % recommended dose of fertilizer and 50% RDF + 50% N as farmyard manure, respectively. However, all the organic based treatments showed significant improvement in soil nutrient status like organic carbon, total nitrogen, available phosphorus and available potassium.

A field investigation was carried out during kharif seasons of 2016 and 2017 at research farm of College of Agriculture, Central Agricultural University, Imphal, to study the influence of integrated nutrient management on dry matter production, yield and NPK content of transplanted rice. The treatments were laid out in a randomized block design and replicated thrice using the rice variety (CAU-R1). Among the different treatments, higher dry matter production and N content in rice were found significantly in T8 (100% RDN from urea + 10 tonnes Azolla ha -1 ) on 30 th , 60 th and 90 th DAT. At harvest, significantly higher content of N in grain was observed in T10 (75% RDN from urea + 25% RDN from FYM + 10 tonnes Azolla ha -1 ) while treatments T8 and T10 showed the similar effect in straw N content. However, statistically higher P concentration was recorded in T11 (50% RDN from urea + 50% RDN from FYM + 10 tonnes Azolla ha -1 ) throughout the growing period and also in grain and straw at harvest time. T12 (25% RDN from urea + 75% RDN from FYM + 10 tonnes Azolla ha -1 ) noted the highest K concentration in grain followed by T11 while K content in straw was highest in both the treatments T11 andT12. In contrary to P content, the K content recorded in grain was low under different treatments. Critical analysis of the pooled data showed that soil treated with 75% RDN from urea + 25% RDN from FYM + 10 tonnes Azolla ha -1 (T10) yielded significantly higher grain and straw yield of rice.