Madras Agric. J. 91 (1-3) : 150-152 January-March 2004 Research Notes

Effect of organic mulches on the weed control efficiency in sugarcane M. JAYACHANDRAN, G. SUDHAKAR AND S. GIRIDHARAN Sugarcane Research Station, Tamil Nadu Agricultural University, Cuddalore - 607 001, Tamil Nadu Sugarcane being cultivated at relatively wider spacing, offers ample scope for weeds to come up along with crop, which results in an intense crop-weed competition resulting in poor yield. The percentage yield reduction due to weeds in sugarcane was estimated as 14 to 75 per cent (Kanwar et al. 1992). However, the growth during its germination phase, sugarcane takes more time to cover the interspaces and hence, a weed free environment during the germination and tillering phases (0 to 90 days after planting) is important for getting higher yield (Ponnusamy et al. 1996). Pulses, if intercropped in the sugarcane, which quickly cover the wide interspaces in between two cane rows and instead offering competition, utilizes the unused growth factors and suppress the emerging weeds through minimizing competition and shading thus minimizing their adverse effect on main crop. Hence, for enrichment of soil organic matter and weed control in sugarcane, an attempt was made to use can trash, pressmud and intercrops as organic mulches to identify a low cost and easy agro technique to replace the pre-emergence spray of atrazine application to sugarcane. Field experiments were conducted at ten sugar factory areas under Coordinated Agronomic Experiment on sugarcane in the Cuddalore region during 1998-99 and 1999-2000 with COSi 95071 as a test variety. The experiment consisted of six treatments viz. (1) use of raw pressmud as mulch at 25 t ha-1, (2) intercropping cowpea in two lines along the ridges mulch and incorporated 60 days after planting, (3) trash mulching at 5 t ha-1, (4) intergrated use of herbicide atrazine 1 kg ha-1 plus one hand weeding on 55 days after planting, (5) farmers' practice of three hand hoeing at 25,55 and 85 days after planting and (6) control (unweeded). The experiments were laid out in randomized block design with

four replications. Recommended dose of N, P and K were applied uniformly, P as basal and N and K in three equal splits on 30,60 and 90 days after planting. Except the farmers' practice, all the other treatments were imposed uniformly on the third day after planting. The observations on germination, weeds and tillers were recorded at appropriate time. The cane yield and quality were recorded at the time of harvest. The weed flora of the experimental field was also recorded and presented below. ------------------------------------------------------S.No. Name of the weed flora ------------------------------------------------------1. Trianthema portulacastrum 2. Tribulus terrestris 3. Portulaca oleracea 4. Panicum repens 5. Cleome viscosa 6. Convolvulus arvensis 7. Croton sparsiflorus 8. Cyanotis cuculiata 9. Cynodan dactylon 10. Cyperus rotundus 11. Asterocantha longifolia 12. Merremia gangetica 13. Sorghum halepense 14. Amaranthus viridis 15. Dactyloctenium aegyptium 16. Commelina bengalensis 17. Chenapodium album 18. Phyllanthus niruri 19. Phyllanthus madraspatensis 20. Ipomea spp. ------------------------------------------------------The quality parameters were analyzed (Meade and Chan, 1977) and the data collected were pooled and analysed statistically (Panse and Sukhatme, 1978). Population of weed species present in quadrates (50 cm x 50 cm) from two spots were recorded and the weed control efficiency (WCE) was worked out by using the formula as follows :

151

-

-

8.36

1.26 8.59

-

-

68.5

3.77

Farmers practice (Three hoeing)

Control (unweeded)

CD (P=0.05)

5.

6.

22.40

82.4

66.9 77.2

Integrated use of atrazine 1 kg ha-1 plus one hand weeding on 55 DAP 4.

2,16,200

0.50

2.61 11.75 115.7

67.8 77.1 Trash mulching @ 5 t ha-1 3.

3,66,200

63.8 71.8 76.1 77.8 Co 5 cowpea as intercrop (two lines along the ridges) 2.

3,57,300

10.15

2.63 12.34 10.42 118.4

112.8 128.5 3,36,300 3,69,200

10.11

2.61 2.90 11.24 15.28 9.97 11.99

2.64 13.05 62.5 76.0 Raw pressmud as mulch @ 25 t ha-1 1.

3,49,900

119.0

11.62

Benefit cost ratio Sugar yield (t ha-1) Commercial cane sugar (%) Cane yield (t ha-1) Tiller prodn./ hectare Weed control efficiency (%) Germination (%) Treatments S.No.

Table 1. Effect of organic mulches on yield and quality of sugarcane (Pooled data of two plant crop 1999-2000 and 2000-2001)

Effect of organic mulches on the weed control efficiency in sugarcane

Wc – Wt WCE = ------------- x 100 Wc Where Wc is the average weed count per unit area in the unweeded check plot Wt is the average weed count per unit area in the treated plots Weed species in the experimental field revealed that the Cyperus rotundus, Cynodon dacytlon, Portulaca oleraceae and Trianthema portulacastrum were the predominant weed species found to 78 per cent and the annual grasses and broad leaved weeds constituted 22 per cent of the total weed population. Trash mulching @ 5 t ha -1 on the ridges of the sugarcane significantly recorded lower weed population and resulted in the highest weed control efficiency of 71.8 and was on par with integrated use of herbicide atrazine 1 kg ha-1 plus one hand weeding on 55 days after planting and farmers' practice which recorded 67.8 and 66.9 per cent weed control efficiency respectively. Weed control efficiency was minimum (62.5%) when raw pressmud @ 25 t ha-1 was applied as mulch. This perhaps may be due to inadequate quantity of pressmud used as mulch material. There was a marked influence on germination of setts due to the treatments. The maximum germination per cent was registered in the trash mulch @ 5 t ha-1 (77.8%) followed by farmers' practice (77.2%) and integrated use of atrazine 1 kg ha-1 plus one hand weeding on 55 days after planting (77.1%). Significant variation could be seen in tiller production due to the treatments. Trash mulching @ 5 t ha-1, farmer's practice and integrated use of herbicide atrazine 1 kg ha-1 plus one hand weeding on 55 days after planting produced almost equal number of tiller per hectare and were on par with each other as compared to rest of the treatments. Intercropping cowpea CO 5 in two lines on the ridges although registered 63.8 per cent weed control efficiency affected tiller production and there was a decline to the tune of 8.16 per cent as compared to the farmers' practice. This may be due to the smothering

152

M. Jayachandran, G. Sudhakar and S. Giridharan

nature of cowpea on the production of tillers as compared to others. The cane yield was found to be highly influenced due to the treatments. Trash mulching @ 5 t ha-1 registered significantly superior cane yield of 128.5 t ha-1 as compared to the rest of the treatments. This is due to the greater weed control efficiency and provision of adequate moisture and nutrients to the crop, which resulted in enhanced cane yield as compared to the other treatments. The next best treatment was raw pressmud @ 25 t ha-1 applied as mulch, which recorded 119.0 t ha-1 of cane yield. This perhaps may be due to the contribution of essential nutrients present in the pressmud that influenced the cane yield. The data showed significant difference between the treatments. Trash mulching @ 5 t ha-1 recorded the highest value of 11.99 per cent commercial cane sugar and was on par with raw pressmud at 25 t ha-1 applied as mulch (11.62%). These two treatments were superior to the rest of the treatments. Intercropping cowpea CO 5 in two lines on the ridges drastically reduced the value of commercial cane sugar per cent as compared to others. Trash mulching @ 5 t ha-1 exhibited the best influence on sugar yield. It recorded the maximum value of 15.28 t ha-1 of sugar yield and significantly superior to all other treatments. Trash mulching @ 5 t ha-1 gave the highest benefit cost ratio of 2.90 and it was followed by raw pressmud 25 t ha-1 applied as mulch and integrated use of herbicide atrazine 1 kg ha-1 plus one hand weeding on 55 days after planting with a benefit

cost ratio of 2.64 and 2.63 indicating their advantage compared to other treatments. Among the treatments tested, trash mulching @ 5 t ha-1 as mulch on the ridges of sugarcane recorded effective weed control with a weed control efficiency of 71.8 per cent, produced higher number of tillers (3,69,200) per hectare and resulted in enhanced cane and sugar yield to the tune of 11.06 and 30.04 per cent respectively with highest benefit cost ratio of 2.90 over the rest of the treatments. However raw pressmud @ 25 t ha-1 as mulch even though registered minimum weed control efficiency of 62.5 per cent, had enhanced cane and sugar yield to the tune of 2.85 and 11.06 per cent over others due to the contribution of essential nutrients present in it. References Kanwar, R.S., Sarjitsingh Sodhi, R.S. and Garcha, A.I.S. (1992). Comparative performance of different herbicides combination for weed control in sugarcane. Indian Sugar XLII: 621-625. Meade, G.P. and Chan, J.C.P. (1977). Cane sugar handbook 10th edition John Wiley and Sons. Inc. New York. Panse, V.G. and Sukhatme, S.V. (1978). Statistical methods for agricultural workers. ICAR, New Delhi. Ponnusamy, K., Santhi, P. and Sankaran, S. (1996). Effect of timing "One weeding" on growth and yield of sugarcane. Philippines Sugar Commun.Q. 2: 47-50.

(Received: December 2002; Revised: April 2003)

Madras Agric. J. 91 (1-3) : 152-155 January-March 2004 Research Notes

Identification of efficient cropping zones for important crops grown in Tamil Nadu N. THAVAPRAKASH Department of Agronomy, Tamil Nadu Agricultural University, Cuddalore - 607 001, Tamil Nadu An analytical study was made at Tamil Nadu Agricultural University, Coimbatore during 2002 to identify the efficient cropping zones (ECZ) for important crops of Tamil Nadu.

At present the uneconomic crops grown in an area has to be replaced by the economically beneficial crops to achieve the self-sufficiency and also sustainability. Growing efficient crops