Validation of common salt application on

Indian Journal of Traditional Knowledge Vol. 16(2), April 2017, pp. 341-349

Validation of common salt application on productivity, profitability, nutrient uptake and soil health of upland rice (Oryza sativa L.) under shifting cultivation area of Nagaland Rakesh Kumar1*, Dibyendu Chatterjee2, Bidyut C Deka3 & SV Ngachan4 1

Indian Council of Agricultural Research, Research Complex for Eastern Region, Patna, Bihar -800 014, India; 2 Indian Council of Agricultural Research, National Rice Research Institute, Cuttack, Odisha-753 006, India; 3 Indian Council of Agricultural Research, Agricultural Technology Application Research Institute, Umroi Road, Umiam, Meghalaya -793 103, India; 4Indian Council of Agricultural Research, Research Complex for North Eastern Hill Region, Umroi Road, Umiam, Meghalaya -793 103, India E-mail: [email protected] Received 26 February 2016, revised 1 June 2016 A replicated field experiment with rice cv. bhalum-3 (130-140 day’s duration) was conducted during the kharif season of 2012-2014 at farmer’s jhum field, Medziphema village, Dimapur district of Nagaland. Experiment was conducted following 12 treatment imposed in completely randomized block design with three replications: control/weedy check, weed free check, 20-200 kg NaCl ha-1 (2-20 % common salt conc.). Experimental results revealed that weed free check showed its superiority in respect to growth, yield attributes, yield, economics, nutrient content and uptake as well as soil health over control and different levels of common salt applied (2-20 %). However, among levels of common salt, application of 10 % common salt recorded significantly higher growth and yield attributes, which was found to be statistically at par with 12-20 % salt applied. Similarly, higher grain yield (2316 kg ha-1), straw yield (3589 kg ha-1) and biological yield (5949 kg ha-1) were recorded with application of 10 % common salt, which was noted significantly superior to their preceding levels (2-8 % NaCl) and beyond that effect of applied salt was found to be statically at par (12-20 %). In respect of soil health, application of common salt does not exert any marked influence on sodium (Na+) concentration, exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR). Keywords: Validation, Common salt, Jhum rice, Grain yield, Soil health IPC Int. Cl.8: A01, C01D 40/00, A01B, A01G 31/00, A01D

The green revolution vastly increased the productivity of resource-poor and well-to-do the farmers by using improved technology in India, but it did little change in the productivity of resource-poor farmers, those who are residing in far flung and risk prone agroecosystem. Upland rice is an important system of rice culture constituting ~1/6th of the world total cultivated land. It is the life and prince among cereals crops, as this unique grain helps to sustain ~2/3rd of world population. More than half of the world population relies on it for energy, fibre and antioxidant, vitamins and minerals, which is essential for life1. In India, it is grown as direct seeded in rainfed condition in an area of ~6.15 m ha, which account~16 % of the total rice acreage2. It is the staple food for people of North East India and extensively cultivated in lowland, upland —————— *Corresponding author

and deep water condition3. In North East India, upland direct seeded rice is grown in more than 2/3rd of the total cropped area4. In Nagaland, upland rice is grown in high land; slope of shifting cultivation and on terrace land, occupying ~70 % of the total cropped area5. In spite of high acreage of upland rice in North East India, its productivity is low due to the severe weed infestations during their entire cropping period. However, weed causes tremendous reduction in yield ranging from 15-65 % depending on methods of crop raising, weed species, density and crop stages at which competition with weeds occurs6. Most of the farmers grow crops in hilly regions without applying any synthetic chemicals and pesticides. Because of intermittent occurrence of rain in early growth stage of rice, weeds like Borreria hispida Spruce ex K. Schum., Ageratum conyzoides L., Amaranthus viridis L., Chromolaena odorata (L.) R.M. King & H.Rob.,

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Commelina benghalensis L., emerge early, grows rapidly and results in heavy weed infestation within short span7. Due to lack of appropriate and location specific technology, resource poor and tribal farmers have evolved their location specific knowledge associated with various crops8. The farmer in North East regions including Nagaland manages the weeds manually, restricting its feasibility especially at peak weeding period. Owing to non-availability of labours at critical physiological stages and high expenditures on labour forces in upland rice cultivation, sometimes it becomes unprofitable. However, extremely acidic soil condition in shifting cultivation areas helps in controlling the weeds with use of common salt since time immemorial9. Jhum farmers of these regions traditionally used to apply salt in upland jhum rice as post-emergence spray to manage annual broad leaf weeds9. Common salt is not a recommended herbicide to control the broad leaved weed; however, alien weeds e.g. Ageratum conyzoides L. and Parthenium hysterophorus L. have been successfully controlled with application of 15-20 % salt7. The modern commercial weedicides like, 2, 4-D and conventional salt are all sodium based and is widely used as postemergence broad leaved weed and sedges control9. Like common salt, application of 2, 4-D can kill even sedges up to 90 % besides increase crop yield significantly10. This might be due to specific physiological adaptations in paddy make it relatively resistant to the salt than broad leaved weed species. However, in subsequent cropping, growth of narrow leaved weeds increased more than normal in salt treated plot11. Since the farmer’s is applying salt in upland jhum fields to manage the weeds in rice, still time and levels of common salt application have not been accredited. Looking to the importance of indigenous knowledge of the farmers, therefore, an effort have been made to validate the indigenous technical knowledge of weed management in upland jhum rice for improving the productivity, profitability, nutrient uptake and effect on soil health to evolve a realistic weed management approach in shifting cultivation area of Nagaland. Methodology A replicated field experiment with rice cv. bhalum3 (130-140 days) was conducted during the kharif season of 2012-2014 at farmer’s jhum field, Medziphema village in Dimapur district of Nagaland. Experimental site was located between 25°45.929′N latitude and 93°53.123′E longitude at an elevation of

508 m above msl and on slope of 55 %.The optimum dose for effective weed control is 1 kg of salt (NaCl) dissolved in 12 L of water9 and higher doses of salt more is weed efficacy. But large quantities of salt were found to affect even crop plant too9. It was a matter of great debate among the farmers to standardize doses and time of salt (NaCl) application for weed management in upland jhum rice. Therefore, keeping these things in view, Indian Council of Agricultural Research, Research Complex for North Eastern Hill Region, Umiam had taken initiatives and organized a workshop on “Alternative to Shifting Cultivation” during 29-30 June, 2011 at Indian Council of Agricultural Research, Research Complex for North Eastern Hill Region, Nagaland Centre Jharnapani, Medziphema, Dimapur district of Nagaland. Many participants across the states including state agricultural department, Nagaland Central University as well as various NGOs working in jhum/shifting cultivation areas were participated this programme. Application of salt for weed management in upland jhum rice was strongly raised by the farmers participated in workshop, because farmers of this region used to salt @ 2-20 % NaCl in hapzard way for weed management in jhum rice. Then, a systematic work was started to find out the optimum doses and time of salt (NaCl) application for managing especially broad leaved weeds associated with jhum rice. The special attention was also given that whether it is harmful to crop as well as soil too. Progressive farmers, Mr. Roko, resident of Medziphema village, Dimapur, Nagaland with their own interest, experiment was conducted during the kharif season of 2012-14 on their field with financial and technical assistance rendered by Indian Council of Agricultural Research, Research Complex of North Eastern Region, Umiam, Meghalaya. The harvested produce of crop and other necessary livelihood support were provided to them through Tribal Sun Plan (TSP) Project. The purposive sampling method was followed prior to conducting the experiment8. The experimental plots of 4 m×4 m were made across the hill slope and crop was raised with dibbling the seed @ 60 kg ha-1 at optimum soil moisture. Traditional practices were followed to raise the crop i.e. no application of fertilizers and manures. The following 12 treatment were imposed in completely randomized block design with three replications: control/weedy check, weedy free check, 20 kg NaCl ha-1 or 2 % salt conc., 40 kg NaCl ha-1 or 4 % salt

KUMAR et al.: COMMON SALT APPLICATION ON ORYZA SATIVA L. CULTIVATION IN NAGALAND

conc., 60 kg NaCl ha-1 or 6 % salt conc., 80 kg NaCl ha-1 or 8 % salt conc., 100 kg NaCl ha-1 or 10 % salt conc., 120 kg NaCl ha-1 or 12 % salt conc.,140 kg NaCl ha-1 or 14 % salt conc., 160 kg NaCl ha-1 or 16 % salt conc.,180 kg NaCl ha-1 or 18 % salt conc. and 200 kg NaCl ha-1 or 20 % salt conc. Common salt were applied as foliar spray through flat fan nozzle using water as a carrier @ 500-600 L/ha at 20 and 40 days after sowing (DAS) of the crop.The mean monthly maximum and minimum air temperatures was varied from 22.9-34.4 0C and 8.5-26.5 0C, respectively. The total mean rainfall was received 3001.8 mm during the cropping period. The monthly rainfall was recorded highest in month of August (476.7 mm) followed by July (363.3 mm). The yield attributes and yield of jhum rice was recorded at harvest with following the standard procedures. The economics, i.e., gross returns, net returns and benefit: cost ratio (B: C ratio) of rice were calculated by considering the existing sale prices of input and output at farm. Physicochemical properties of the soil: To evaluate initial fertility status of the soil, composite soil samples from 0-15 cm depth was collected randomly from experimental field with the help of screw auger prior to crop sowing. Then samples was brought to laboratory, air-dried, ground and sieved through 20 mm mesh. The processed soil samples were analyzed for physico-chemical characteristics and results are presented in Table 1. The analysis of variance method for complete randomized block design was followed to analyse difference among the treatment means. Significance of different sources of variation was tested for error mean square of Fisher Snedecor’s F test at probability level (P < 0.05). The means were compared with using Duncan Multiple range Test (DMRT). Results Growth characters Significant differences was observed on growth attributes, i.e., plant height, number of green leaves, Table 1—Physico-chemical properties of the experimental soil Stages

pH

N EC OC P K Moisture (dSm-1) (%) (kg ha-1) (kg ha-1) (kg ha-1) (%)

Before 4.35 0.135 0.951 238.3 burning After 4.73 0.120 0.997 188.1 burning Before 4.84 0.125 0.979 206.9 sowing

6.06

344.96

11.81

12.12

372.96

10.16

14.54

374.08

12.35

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tillers and dry matter production of jhum rice due to application of varying levels of common salt (Table 2). Among the levels of common salt, application of 10 % common salt (NaCl) produced significantly taller plant (111.1 cm), higher number of green leaves (128.1) and tillers plant-1 (57.1) as compared to its preceding levels (2-8 % NaCl) and beyond this effect of applied levels of salt (12-20 % NaCl) was found to be statistically similar except weed free check. However, weed free check recorded significantly higher values of all these growth attributes. Similar trend was followed in case of dry matter production. The treatment weed free check (78.16 gm) followed by 100 kg salt applied ha–1 (54.19 gm) produced highest dry matter plant-1over weedy check. However, mean dry matter with 120-200 kg NaCl applied ha–1 (12-20 % NaCl) was noted statistically at par. The weed free check and salt applied treatments realized 44.2 (weed free check), 15.5 (2 % NaCl), 17 (4 % NaCl), 17.1 (6 % NaCl), 18.5 (8 % NaCl), 32.9 (10 % NaCl), 18.9 (12 % NaCl), 19.3 (14 % NaCl), 20.5 (16 % NaCl), 21.26 (18 % NaCl) and 19 % (20 % NaCl) increment in dry matter production over the weedy check. Yields parameters It was noted that significant differences was recorded in grain and straw yield of jhum rice due to application of different levels of salt (Table 2). Among the levels of salt, application of 10 % NaCl gave significantly higher grain yield (2316 kg ha-1), straw yield (3589 kg ha-1) and biological yield (5949 kg ha-1) of jhum rice compared to their preceding levels (2-8 % NaCl) and beyond that applied salt (12-20 % NaCl) did influenced markedly. The weed free check treatment recorded significantly highest grain yield (2518 kg ha-1), straw yield (3903 kg ha-1) and biological yield (6468 kg ha-1), whereas the lowest grain yield (1765 kg ha-1), straw yield (2735 kg ha-1) and biological yield (4533 kg ha-1) was associated with weedy check. The treatment weed free check and salt applied @ 10 % realized 42.7, 31.2, 42.7 % and 31.22.42.69, 31.23 % increment in grain, straw and biological yield, respectively over weed check. However, grain yield of jhum rice with 120-200 kg applied NaCl ha-1 (12-20 %) was found to be statistically at par. The yield increased to its higher value at 10 % salt and thereafter decreased in all other treatments. The highest crop productivity (19.3kg ha-1 day-1) was recorded with weed free check whereas, among levels of salt, application of 10 % NaCl ha-1 gave markedly higher crop productivity (17.8kg ha-1 day-1) thereafter decreased in all the treatments.

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Table 2—Effect of salt application on growth, yield and economics of upland jhum rice (Pooled data of two years) Treatment Plant Green Tillers Dry matter Grain Straw Bio. HI height leaves m m row-1 Plant-1 (g) yield yield Yield (%) (kg ha-1) (kg ha-1) (kg ha-1) (cm) row-1 (no.) (no.) Control Weed free check 2% Salt conc. 4% Salt conc. 6% Salt conc. 8% Salt conc. 10% Salt conc. 12% Salt conc. 14% Salt conc. 16% Salt conc. 18% Salt conc. 20% Salt conc.

87.4a 119.8

d

114.6a

40.5a

54.1a

1765a

2735a

4533a

c

d

d

d

d

c

139.1

65.7

78.1

2518

3903

6468

COC Gross Net B: C Eco. Crop prod. (`ha-1) return return ratio Effi. (kg ha-1 (` ha-1) (`ha -1) (`ha-1 day-1) day-1)

34.6a 13.5a 46.7

d

19.3

d

15550a 40804a 25254a 2.15a b

d

d

20550 58224 37674 2.60

150a

g

216b

90.5a

115.5a

47.9b

62.6b

2008b

3113b

5160b

41.4b 15.4b

17100a 46444b 29344b 2.21b

169a

95.1a

115.8a

48.6b

63.4b

2075b

3216b

5331b

40.0b 15.9b

17400a 47986b 30586b 2.25c

176a

95.74b

116.1a

48.6a

63.4b

2105b

3263b

5409b

40.3b 16.2b

17700a 48689b 30989b 2.20b

173a

97.48b

116.5a

49.3b

64.1b

2136b

3310b

5487b

41.4b 16.43b

18000a 49387b 31387b 2.29d

185a

111.1c

128.1b

57.7c

72.0c

2316c

3589c

5949c 45.34c 17.81c

18300a 53548c 35348c 2.42f

201b

98.6b

117.1a

49.5b

64.4b

2265b

3510b

5818b

45.0c 17.4c

18600a 52368b 33768b 2.33e

196b

100.2b

117.5a

49.7b

64.6b

2233b

3462b

5738b

47.9d 17.2c

18900a 51648b 32748b 2.26c

193a

100.6b

117.6a

50.3b

65.3b

2232b

3459b

5733b

46.1c 17.1c

19200a 51608b 32408b 2.35e

195b

101.8b

118.2a

50.7b

65.71b

2214b

3431b

5688b

46.5c 17.0c

19500b 51196b 31696b 2.31d

185a

102.1b

118.6a

50.9b

65.9b

2211b

3426b

5679b

46.9c 17.0c

19800b 51119b 31319b 2.28d

189a

*Bio.: Biological, COC: cost of cultivation, HI: Harvest Index, B: C ratio: Benefit: cost ratio, Crop Prod. : Crop Productivity, Eco. Effi. : Economic efficiency, within each levels of salt application, within each characters, means followed by different letters are significantly different (P < 0.05; DMRT)

Economics Among the levels of common salt, the maximum gross returns (` 53,548 ha-1) was recorded with application of 10 % salt except weed free check (`58,224 ha-1) and beyond that applied levels of salt could not influenced markedly (Table 2). Similarly, maximum net returns (`35,248 ha-1) was noted with application of 10 % salt compared to preceding levels (2-8 % NaCl) but salt applied beyond this level (12-20 % NaCl) did not influence significantly. The weed free check treatment recorded the maximum net returns (`37,674 ha-1). The treatment weedy check and salt (NaCl) applied treatments realized 49.2 (weed free check), 16.2 (2 % NaCl), 21.1(4 % NaCl), 27.7 (6 % NaCl), 22.3 (8 % NaCl), 39.9 (10 % NaCl), 33.7 (12 % NaCl), 29.7(14 % NaCl), 28.3 (16 % NaCl), 25.5 (18 % NaCl) and 24 % (20 % NaCl) increment in net returns over weedy check. Nutrient content and uptake The marked influenced on nutrient content and its uptake in jhum rice was noted with application of

different levels of salt (Table 3). Significantly higher values of N, P and K content in grain and straw of jhum rice were associated with weedy free check and lowest with weedy check. The range of N content in grain of rice varies from 1.586-1.727 % and in straw, 1.004-1.414 %. In case of P, content in grain varies from 0.220-0.302 % and in straw, 0.071-0.118 %. Similarly, K content in grain of rice varies from 0.315-0.380 % and in straw, 2.033-2.23 %. In case of nutrient uptake by grain and straw, salt applied @ 10 % recorded significantly higher values of N, P and K uptake but it was found to be statistically at par with 12-20 % salt applied ha-1(Table 3). With respect to total nutrient uptake, jhum rice was markedly influenced with application of varying levels of salt (Fig. 1). Among the levels of salt, total N uptake (77.6 kg ha-1), P uptake (8.2 kg ha-1) and K uptake (86.6kg ha-1) were recorded markedly higher with salt applied @ 10 %, which was noted statistically at par with 12-20 % NaCl and per cent increases by 39.9, 39.8 and 41.7 %, respectively over the weedy check.

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Table 3—Nutrient content and uptake of upland jhum rice as influenced by levels of salt application (Pooled data of two years) Treatment Nutrient content (%) Nutrient uptake (kg ha-1) N Control Weedy free check 2% Salt conc. 4% Salt conc. 6% Salt conc. 8% Salt conc. 10% Salt conc. 12% Salt conc. 14% Salt conc. 16% Salt conc. 18% Salt conc. 20% Salt conc.

P

K

N

P

K

Grain

Straw

Grain

Straw

Grain

Straw

Grain

Straw

Grain

Straw

Grain

a

a

a

a

a

a

a

a

a

a

a

1.586 1.727b 1.570a 1.590a 1.610a 1.620a 1.690a 1.650a 1.670a 1.650a 1.660a 1.670a

1.004 1.141b 1.010a 1.030a 1.050a 1.060a 1.070a 1.040a 1.050a 1.020a 1.050a 1.060a

0.220 0.302b 0.224a 0.225a 0.226a 0.227a 0.229a 0.224a 0.226a 0.224a 0.227a 0.226a

0.071 0.118b 0.072a 0.074a 0.075a 0.076a 0.079a 0.077a 0.076a 0.078a 0.074a 0.077a

0.315 0.380b 0.319a 0.327a 0.338a 0.339a 0.347a 0.320a 0.325a 0.330a 0.321a 0.345a

2.033 2.230b 2.160a 2.170a 2.175a 2.180a 2.190a 2.185a 2.188a 2.193a 2.195a 2.147a

28.00 27.50 43.48c 44.52c 31.53a 31.44a 33.19a 33.32b 33.967b 34.33b 34.61b 35.10b 39.18b 38.45b 37.45b 36.59b 37.32b 36.37b 36.88b 35.34b 36.770b 36.050b 36.940b 36.34b

3.89 7.60c 4.50a 4.69b 4.76b 4.85b 5.31b 5.08b 5.05b 5.00b 5.02b 4.99b

1.93 4.61c 2.24b 2.39b 2.45b 2.51b 2.839b 2.70b 2.63b 2.68b 2.54b 2.64b

5.57 9.57c 6.40a 6.82b 7.13b 7.24b 8.06b 7.26b 7.26b 7.37b 7.11a 7.61a

Straw 55.56a 87.08c 67.25b 70.21b 71.12a 72.195b 77.559b 76.88b 75.78b 75.98b 75.36b 73.53b

Fig. 1—Total nutrient uptake of upland jhum rice as influenced by different levels of common salt application (Pooled data of two years)

Soil health The Fig. 2 shows sodium (Na+), exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR) status after different rates of NaCl applied in soil. Sodium (Na+) concentration (0.061 meq 100 g-1) in weed free check treatment was recorded statistically similar to Na+ concentration (0.055 meq 100 g-1) with weedy check. The ESP was noted to be less in weedy check than weed free check and salt treated plots. The value of ESP and SAR increased slightly at 18-20 % NaCl as compared to other treatments. Discussion Growth characters Significant differences was observed on growth attributes i.e. plant height, tillers and dry matter

production of upland jhum rice with application of 10% salt except the weed free check. Since, the farmers do not adopt any synthetic pesticides, 3-4 times manual weeding is recommended during the cropping period of jhum rice. But this practice incurs high labour cost and increased cost of production and same time decreased their net income. Thus, the farmers adhere to their ethnic custom of application of salt (NaCl) for controlling the weeds in jhum rice. The farmers prefer salt to kill the weeds because of its ready availability, low cost, safe use and traditional belief. Common salt affects plant by three modes of action: lowering of water potential, direct toxicity of Na+ and Cl–ions and interference with uptake of essential nutrients9. The high Na+: K+ ratio disrupts various enzymatic processes in cytoplasm owing to

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Fig. 2—Soil health of upland jhum rice as influenced by different levels of common salt application (Pooled data of two years)

ability of Na+ to compete with K+ for binding sites12. However, silica deposition and polymerization of silicate in endodermis and rhizodermis block Na+ influx through apoplastic pathway in roots of rice13. Thus, rice can regulate, adjust its osmotic pressure and can thrive well in higher salinity. Available reports suggest that globally salt is applied to control smooth crab grass [Digitaria ischaemum (Schreb.) Muhl.]14, goose grass [Eleusine indica (L.) Gaertn.]15, sour grass (Paspalum conjugatum P.J.Bergius)16, annual grass weed17. Also, sea water is sprayed to control weed in turf grass18. As a cost-effective strategy, salt is mixed to reduce rate of round-up application in oil palm plantations19. The better performance of growth characters of jhum rice in weed control treatments was due to enhance crop growth attributes and effectiveness of chemicals to manage the weeds17-19. Yields attributes Application of salt (NaCl) recorded an increase of yield but trend followed ‘Law of Diminishing Return’. The yield increased to its highest value at 10 % NaCl and thereafter decreased in all other treatments. Increase in yield could attribute to increase in growth and yield attributes viz. number of tillers, dry matter, number of panicles m-2 and panicle length along with decrease in chaffy grains in controlled plot7,20-24. Similarly, application of salt up to 150 kg ha-1 recorded significantly higher grain yield due to better performance of yield attributes of upland jhum rice7, 24. Another reason could relate to

salt tolerance of rice that since, it mobilizes its food reserves (polysaccharides) into growing regions to exert the tolerance against salt application. Once polysaccharides mobilized, they converted into its monomers, i.e., sucrose, fructose and glucose that were readily transportable to the sites, where they required for growth and development. Actually, these soluble monomers could regulate osmotic pressure of the cells9. Actually, broadleaved weed species are highly sensitive to salinity and these species can be controlled with application of common salt25. In Odisha, this practice in rice has shown 60% effectiveness in controlling the weeds26. Economics Economics was computed to check the best weed management practices among statistically similar treatments in terms of yield. Common salt (NaCl) was noted the best weed management strategy in terms of comparatively higher profits9. The literature reveals that common expenditure incurred in jhum rice is ` 7500 ha-1 as against salt treatment (`5000 ha-1), which have marked influence in jhum rice production9 and same time farmers reduced their cost of production and increase net income. Though, gross and net returns were higher in hand weeding but incurring of high expenditure in terms labour cost reduced the monetary returns in hand weeded24. The salt application markedly influenced economics of jhum rice by increase in unit level of salt applied up to 100 kg ha-1 but decreased thereafter (Table 2). Weed free check treatment recorded maximum net returns (`37,674 ha-1). However, this treatment incurred

KUMAR et al.: COMMON SALT APPLICATION ON ORYZA SATIVA L. CULTIVATION IN NAGALAND

higher cultivation cost and associated with lower benefit: cost ratio (B: C ratio) due to increase in labour cost. Similar findings were also reported in upland jhum rice by various researchers in their investigation20-24. Similarly, application of 10% salt gave markedly higher B: C ratio (2.42) and economic efficiency (201ha-1day-1). Similar results were confirmed in jhum rice7,21,24. Nutrient content and uptake Common salt applied with varying doses markedly improved N, P and K content and their uptake by jhum rice than weedy check (Table 3). The weed management through application of common salt assures more mining the available nutrient from the soil in adequate amounts; hence, the crop produced healthy and more vigorous plant. Such healthy and vigorous plant accompanied with higher concentration of N, P and K ascertained greater uptake of these nutrients in jhum rice. Increase in uptake of these components is combined effect of substantial increase in concentration of these parameters in grain and straw is influence by increasing levels of salt applied. Soil health Shifting cultivation is practiced as a combination of 1-3 yrs of cropping and 10-15 yrs of fallow period in Nagaland, because productivity of crops reduces after one cropping. Besides, paddy as many as 60 crops have been reported to be cultivated in jhum field27, 28. The farmers of region used to cultivate crops on hillock without applying any synthetic pesticides and fertilizers. The jhum cultivation is the most prevalent practices by the Nāga ethnic groups for their livelihood. In this system, a part of the forest is slashed, burnt and cropped without tilling soil, and land is fallowed subsequently to attain the pre-slashed forest status through natural succession29. Besides, the farmers cultivate crops in the virgin forest land after clearing native trees and shrubs. Thus, menace of weeds is much higher than conventional cultivation because soils are aerobic in nature and it favours prolific growth of weeds7. As a consequence, productivity of rice in Nagaland is far lesser than other parts of India. It was observed that applied salt (NaCl) did not exert an undesirable influence on sodium (Na+), exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR). The ESP and SAR increased slightly at 18-20 % NaCl in the first year but in second year of experimentation, this effect was nullified. The higher precipitation coupled with steep slopes reduced salt concentration from soil and

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differences in timing and intensity of precipitation after salt application, amount and type of ground cover would affect the extent to which salt was available on soil surface24. Conclusion It has been concluded that tribal farmers of this region have location specific ecological knowledge of traditional weed management in upland jhum rice for increasing crop productivity. They select and conserve this valuable knowledge on account of socio-cultural and environmental condition, thus farmer’s innovations viz. application of salt has considerable adaptability under risk prone agroecosystem. These commonly followed local practices of weed management by tribal community in upland jhum rice respond to applied salt and crop yield is increased without having any negative effect on crop growth as well as soil health. This common practice helps the tribal farmers to increase their net income and improve socio-economic status. This valuable knowledge also helps in discouraging the farmers to use higher doses of salt and manual weeding, which have more practical difficulties because of steep slope on hillock. To enhance the conservation of such indigenous knowledge through increasing productivity of jhum rice, role of plant breeder, biotechnologist, physiologist, soil scientist as well as agronomist would be required in leading manner to make these practices more productive, lucrative and competitive to manual weeding. These findings can be utilized to formulate the hypotheses for designing and implementing research project on location specific and farmer’s knowledge based participatory research for efficient natural resource management in fragile agro-ecosystem of North East India. The environmental managers can incorporate such elements as component of system-level approach to natural resource management, where biological, social, cultural, economic and symbolic aspect is nested within a broader socio-ecological system. The practice of using common salt for weed management in upland jhum rice is cost effective as compared to commonly followed 3-4 times manual weeding during the cropping period. Application of common salt does not show any harmful effect on yield of upland jhum rice in acidic soil of Nagaland. The markedly higher rice yield was noted with 100 kg salt applied ha–1, However, weed free check i.e. weed managed by manually has highest net monetary return, but this treatment has practical difficulties because of steep

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slope. Considering economics and ease in the method, application of 100 kg salt ha–1 (10 % NaCl) may be recommended for managing the annual broad leaved weeds in upland jhum rice. However, acidic soil of jhum land have not shown any deteoriation in its quality, i.e., sodium (Na+), exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR), but care must be taken while repeated application of salt at higher dose to avoid harmful effect in long run in hill ecosystem of Nagaland. Acknowledgement This institute project was approved and supported by ICAR Research Complex for North Eastern Hill Region, Umiam. Authors are highly thankful to the farmers of Mon, Longleng, Wokha, Kohima and Dimpaur district of Nagaland for sharing their valuable knowledge and expertise on indigenous traditional knowledge of salt application in jhum rice for weed management. Author’s special thanks to Mr. Roko, Progressive farmers of Medziphema village, Daimpur, Nagaland in terms of providing the valuable piece of land for testing the effect of common salt for weed management in jhum rice and soil health. The authors also thank to esteemed editors and referee for revision of the manuscript whose comments and advice has greatly enhanced this article. References 1

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