Non-herbicidal Weed and Organic Nutrient Management in Maize under Rainfed Maize-Sesamum Cropping Sequence

During 2013 and 2014, a field experiment was performed in the InstructionalCum-Research Farm, Assam Agricultural University, Jorhat to study the effect of weed and nutrient management in maize on weeds and maize, sesamum yield. The field experiment was conducted in split plot design (SPD) and the treatments comprised of fertility management (F0 control, F1 2.5 t/ha enriched compost and F2 5.0 t/ha enriched compost) as the main factor and weed management (W0-no weeding, W1hand hoeing and earthing up 20 and 50 days after sowing,W2-in situ cowpea mulching upto 50 days after sowing and W3in situ blackgram mulching upto 50 days after sowing) as the sub factor in maize and its residual effects tested in subsequent sesamum crop. It was found that W1 resulted in the least weed NPK content (%) at 60 days after sowing (DAS). In case of NPK uptake (kg/ha), W1 resulted in the least at 60 DAS and harvest. It was also noticed that W2 caused the least weed NPK content (%) at harvest during both the years. Organic nutrition had no effect on the above mentioned parameters. The residual effect of weed management and organic nutrition in the subsequent sesamum crop was nil in terms of weed suppression. It was found that W1, F2 and W1F2 resulted in significantly the best LAI of maize for both the years. Treatments W1 (3014.59 kg/ha and 2849.24 kg/ha in 2013 and 2014, respectively), F2 (2322.33 kg/ha and 2178.29 kg/ha during 2013 and 2014, respectively) and W1F2 (4723.81 kg/ha and 4507.24 kg/ha during 2013 and 2014, respectively) too resulted in significantly the highest grain yield of maize. No residual effect of weed management was found while organic nutrition had residual effect in sesamum crop. The best LAI in Current Agriculture Research Journal www.agriculturejournal.org ISSN: 2347-4688, Vol. 8, No.(3) 2020, pg. 193-207 CONTACT N. Khumdemo Ezung kvkkiphire2017@gmail.com KVK, Kiphire, ICAR for NEHR, Nagaland Centre, India. © 2020 The Author(s). Published by Enviro Research Publishers. This is an Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC-BY). Doi: http://dx.doi.org/10.12944/CARJ.8.3.05 Article History Received: 04 March 2020 Accepted: 09 October 2020


Introduction
Maize is the third most important food grain followed by rice and wheat in India. Maize is used for human consumption both with and without industrial processing, as animal feeds and bio-chemical industries. Maize is called as the queen of cereals due to its high yielding ability. Maize is mostly cultivated during rainy season in our country and weeds are a major problem during this period of time because of amble availability of growth factors during this season. Several research workers had observed that if weed competition in maize was left unchecked it would result in serious yield loss. 1,2,3 Weed management strategies are focused on reducing the deleterious competition of weeds growing with crop plants for growth factors. 4 It is a well documented fact that due to rise in environment pollution, various human health related issues have arisen which have led the human race to advocate for reduction in the pollution for a greener earth. Agriculture too has a share in the contribution towards environment pollution through the indiscriminate use of synthetic agro-chemicals. Researchers are constantly working on bringing out techniques that would curtail the agriculture dependence on synthetic agro-chemicals while not compromising with the issue of feeding the ever growing population on earth. Manual weeding followed by earthing up, 5 hoeing twice 6 and live mulching combined with hand weeding 7 were documented to be effective in suppressing the weeds in maize. In India, maize-wheat or maize-rapeseed rotations are prevalent. Maize is usually mono cropped or in cultivated in rotation with greengram or blackgram in Assam. 8 The farming in the North eastern region is organic by default as the application of fertilizers and pesticides are limited compared to the other regions of the country. Maize organically cultivated may be followed by sesamum crop, an important oilseed crop of India which have a low nutrient requirement. 9 Researcher 10, 11 have noticed residual effect of compost application in different cropping sequence. Researches on non-herbicidal weed and organic nutrient management in maizesesamum cropping sequence in Assam are lacking. Considering all the points discussed above, the present experiment was done.

Materials and Methods Site Location
During the year 2012-2013 and 2013-2014, the field experiment was done at the Instructional-Cum-Research (ICR) farm, Assam Agricultural University, Jorhat.

Treatments, Layout and Initial Soil Chemical Status of the Experimental Field
The experiment was conducted in split plot design. The main factor was fertility management (F 0 -control, F 1 -2.5 t/ha enriched compost and F 2 -5.0 t/ha enriched compost) and the sub factor was weed management (W 0 -no weeding, W 1hand hoeing and earthing up 20 and 50 days after sowing,W 2 -in situ cowpea mulching upto 50 days after sowing and W 3 -in situ blackgram mulching upto 50 days after sowing). The treatments were incorporated in maize and its effects were carried over to the succeeding crop sesamum. The enriched compost was procured from the department of soil science, Assam Agricultural University, Jorhat. Enrichment was done by addition of rock phosphate. The research plot soil was sandy loam in texture with acidic in reaction (pH 5.33). The soil organic C value was 0.51%, available N was 318.93 kg/ha, available P 2 O 5 was 32.95 kg/ha and available K 2 O was 167.54 kg/ha. 9,12 Crop Varieties Used Varieties used in the experiment were as follows, maize variety-Dekalb 900 m Gold, sesamum-Koliabor Til, cowpea-UPC-212, blackgram-T9. 9,12 Weed Analysis The weeds present within a quadrate (50 cm x 50 cm) placed randomly at four locations in each individual plot were removed at 60 days after sowing (DAS) and during harvest of maize and sesamum. The weeds were cleaned and oven-dried at 60±5°C to constant dry weight, finely grounded with a grinding machine and chemically analysed for NPK content. The methods of chemical analysis followed were- For the total NPK uptake by weeds, it was calculated using the following formula: Nutrient uptake = [Nutrient content/100] × Biomass (kg/ha)

Growth Analysis
In case of maize, length of the fully opened leaf lamina was measured from the base to the tip. Leaf breadth was taken at the widest point of the leaf lamina. The product of the leaf length and breadth were multiplied by the factor 0.75 14

Yield Analysis
At physiological maturity, maize cobs from each net plot were harvested. Cobs were separated, air dried, shelled, cleaned and weighed. Grain yield per ha was worked out and expressed in kg/ha. In sesamum, during harvest, net plot was harvested separately and bundled. Bundles were dried in sunshine. Later seeds were separated from the bundles separately for each individual plot manually by tapping with a stick. The produce was dried, winnowed, cleaned and weight of seeds obtained from each net plot was recorded expressed in kg/ha.

Benefit:Cost Ratio Analysis
This was calculated by dividing the net retun by total cost of cultivation.

Statistical Analysis
All the data pertaining to the present investigation was analysed following the procedure of analysis of variance. 16 Significance or non-significane of variance was determined by calculating respective 'F' values. Whenever the variance ratio (P) was found significant, critical difference (CD) was worked out at 5% probability level.

Results and discussion Content (%) and Uptake (kg/ha) of NPK by Weeds in Maize at 60 days and at Harvest
Fertility management: The data given in Table 1 and Table 2 revealed no significant effect of fertility management by organic nutrition in maize on content (%) and uptake (kg/ha) of NPK of weeds in maize at 60 days and harvest.

Weed Management
Non-herbicidal weed management in maize resulted in significant effect (

Interaction
No significant interaction effect between fertility management by organic nutrition and non-herbicidal weed management in maize on NPK content (%) and uptake (kg/ha) of weeds in maize at 60 DAS and harvest.
No significant effect due to fertility management on weeds was found in the present experiment. Organic manures had no significant effect on dicot weeds while significant effect was observed only on monocot weeds in fennel. 17 A study of the results on NPK content (%) of weeds revealed that the trend at harvest of maize were totally different as compared to that made at 60 DAS. Significantly more NPK content (%) of weeds at harvest of maize in case of W 1 compared to other treatments.
The soil disturbances at 50 DAS due to W 1 might have encouraged emergence of new weeds later on and their density being less at harvest of maize resulted in more NPK content of weeds. However, it was not detrimental to maize as the critical period of crop-weed competition was over after 50 DAS.
Significantly the lowest NPK content of weeds in case of W 2 was due to smothering of weeds. The findings regarding NPK uptake (kg/ha) of weeds at harvest in maize as described above reflected the similar trend as observed at 60 days. Though low NPK content of weeds was observed in W 2 it could not reduce the weeds NPK uptake. It was due to the fact that this treatment was unable to substantially decrease the weeds density and dry weight. As the density and dry weight of weeds were significantly lesser due to W 1 , uptake of NPK in weeds was found to be significantly lesser too as compared to other treatments. No weeding resulted in the maximum uptake of NP nutrients by weeds in maize as compared to two hand weeding. 18

Content (%) and Uptake (kg/ha) of NPK by Weeds in Sesamum at 60 Days and Harvest
Fertility, weed management and their interaction in maize could not significantly influence the NPK content (%) and uptake (kg/ha) of weeds in sesamum at 60 days and at harvest (Table 3 and Table 4). As in the preceding crop maize fertility management with enriched compost application did not have significant effect on weeds, therefore similar effect in respect of weeds during the sesamum crop was quite obvious. No residual effect of herbicides as well as hand weeding twice applied in rice on succeeding blackgram was observed. 19

LAI, days to 50% Tasseling and Yield of Maize Fertility Management
The LAI, days to 50% tasseling and yield of maize were found to be significantly affected due to fertility management by organic nutrition (

Weed Management
Effect of non-herbicidal weed management was significant (

Interaction
Interaction of the weed and nutrient management had significant effect on the LAI, days to 50% tasseling and maize grain yield ( While considering the same level of organic nutrition (F), W 1 produced the highest grain yield. Taking into account the same or different level of nonherbicidal weed management (W), F 2 resulted in the highest maize grain yield. 12 Amongst the treatment combinations, F 2 W 1 was the best in terms of grain yield of maize during both the years.
Perusal of the results on the effects of the treatments of the present experiment on revealed that LAI, days to 50 % tasseling and yield of maize were significantly improved due to application of enriched compost and non-herbicidal weed management. This was due to the fact that non-herbicidal weed management by W 1 could significantly reduce the weed infestation in maize, and therefore, the growth attributes and ultimately the yield of maize significantly improved by organic nutrition through application of enriched compost in maize. Thus, the combination of F 2 W 1 was found to be significantly the best followed by F 1 W 1 in respect of the growth attributing characteristic and yield. Weed management by W 1 could significantly reduce the weed infestation till the critical period of crop-weed competition in maize thereby giving the opportunity to the maize plants to tap the growth factors from their environment with less stress from the weeds compared to other treatments. The benefits of organic nutrition through enriched compost @ 2.5 t/ha and 5.0 t/ha could only be realised by the effective management of the weeds which were evident by the data obtained. Two hand weeding applied in maize resulted in better growth attributes as compared to no weeding at all4. The efficacy of non-herbicidal methods in managing the weeds and increasing the yield in maize was highlighted by several workers. 20,21,22 Efficiency of organic nutrition in improving the growth and yield of maize was reported by various workers. 23,24 In case of in situ cowpea live mulching, even though the weed NPK content and uptake were significantly reduced compared to in situ blackgram live mulching upto 50 DAS and weedy check, in situ cowpea live mulching proved to be detrimental to the maize plants because it competed with the crop for growth factors thereby negating its weed suppressing ability which was reflected in poor growth of maize plants. In situ blackgram live mulching was poor in suppressing the weeds and thus the combined effect of blackgram plants and weeds depressed the growth of the maize plant. Competition from live mulches for growth factors with the main crop thereby causing yield loss of the main crop had been reported. 25

Lai, Days To 50% Flowering and Yield Of Sesamum Fertility Management
The data revealed significant residual effect of fertility management by organic nutrition in maize on LAI, days to 50% flowering and yield of sesamum ( No residual effect of non-herbicidal weed management on growth characteristics and yield of the succeeding crop sesamum were observed due to weed management of maize. As the weed management during the preceding crop maize was non-herbicidal, its residual effect on weeds of the next crop sesamum was not observed obviously.
No residual effect of hand weeding twice applied in rice on succeding blackgram was observed. 19 On the other hand, distinct residual effect due to fertility management in maize with enriched compost application was observed which was reflected in significantly improved LAI, significantly lesser days to 50% flowering and higher grain yield in sesamum.
Positive residual effects of organic manures in succeeding crops following maize have been reported. 26,10,27 Regarding the significant residual effect of fertility management during maize on growth characteristics of sesamum, it may be explained that due to slow release of nutrients from enriched compost during maize, the residual effect might have been obtained during sesamum. Manures have manifold benefits on the soil physical, chemical and biological characters 28 and have the ability to supply plant nutrient for two or more crop seasons. 29 Therefore, growth characteristics and seed yield of sesamum showed significant improvement due to residual effect of application of enriched compost @ 2.5 and 5.0 t/ha compared to non application of enriched compost.

Comparative Economics of the Treatments In Maize-Sesamum Cropping Sequence
The comparative economics of the treatments in respect of maize-sesamum cropping sequence has been presented in Table 7. It revealed that higher gross return (`292078.33/ha and `255858.67/ha in 2013 and 2014, respectively) and net return (`190310.33/ha and `154090.67/ha) of the sequence were due to application of F 2 W 1 but benefit: cost ratio (2.56 and 2.16 in 2013 and 2014, respectively) was more due to application of F 1 W 1 .
The efficacy of fertility management with application of enriched compost at either 2.5 or 5.0 t/ha and weed management by non-herbicidal methods especially hand hoeing and earthing up at 20 and 50 days in maize-sesamum cropping sequence in controlling weeds and improving growth and yield of the crops has already been highlighted. That is why, application of enriched compost associated with hand hoeing and earthing up at 20 and 50 days proved to be better than the other treatment combinations in this regard. More benefit: cost ratio obtained with application of 2.5 t/ha enriched compost as compared with 5.0 t/ha application may be attributed to the lesser cost of production incurred in case of the former.

Conclusion
Management of weeds by hand hoeing and earthing up twice coupled with organic nutrition by enriched compost in maize would result in profitable maize grain yield while beneficial residual effect of enriched compost application in maize would be observed in subsequent sesamum in terms of better growth and higher seed yield.

Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.