Effect of grass mulching on growth and yield of legumes

Agricultural Water Management, 6 (1983) 375--383

375

Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

EFFECT OF GRASS MULCHING ON GROWTH A N D YIELD OF LEGUMES

J.P. G U P T A

and G.N. G U P T A

Division of Soil-Water-Plant Relationship, Central Arid Zone Research Institute (CAZRI),

Jodhpur 342003 (India) (Accepted 14 December 1982)

ABSTRACT Gupta, J.P. and Gupta, G.N., 1983. Effect of grass mulching on growth and yield of legumes. Agric. Water Manage., 6: 375--383. Field trials were conducted during the wet seasons of 1980 and 1981 to find out the response of legumes to mulch induced soil environment in the arid area of western Rajasthan, India. With increasing amounts of grass mulch there was a decrease in maxi m u m soil temperature and an increase in root growth, nodulation, shoot growth and plant water status, particularly during periods of moisture stress. Mulching reduced weed population and weed growth. At 9 ~t ha-' of mulch there was an increase of 2 0 0 % in the average production of green gram (Vigna radiata), dew gram (Phaseolus aconitifolius) and cluster bean (Cyamopsis tetragonoloba). Though there were no significant differences in water use by the crop, water use efficiency was generally higher in mulched plots. Waste grass therefore can be used favourably as mulching material for increasing crop production.

INTRODUCTION In arid areas of Western Rajasthan, India, grain legumes such as green gram (Vigna radiata), dew gram (Phaseolus aconitifolius) and cluster bean (Cyamopsis tetragonoloba) are grown during the monsoon period (July-September). Most of the rain in these areas is received during this period but it is generally low and erratic. The temperatures are high and the humidity is low leading to high evaporative demand of the atmosphere. Soil temperatures often rise as high as 50--55°C in the upper root zone and seriously affect r o o t growth. This in turn adversely affects the growth and yield of crops. Earlier studies (Gupta, 1978, 1980; Gupta and Gupta, 1982) have shown the usefulness of grass mulch in improving crop production. However, the information on the response of legumes to mulching is lacking. The present study was therefore conducted. MATERIALS AND METHODS

Field trials were conducted with loamy sand soil (sand 85.2%, silt 4.8% 0378-3774/83/$03.00

© 1983 Elsevier Science Publishers B.V.

376

and clay 9.9%) of the Central Research Farm of the Central Arid Zone Research Institute, Jodhpur, during the monsoon seasons of 1980 and 1981. Five levels of grass mulch (0, 3, 6, 9 and 12 t ha -t) were replicated four times in a randomized block design. Green gram (Vigna radiata cv. S-8), dew gram (Phaseolus aconitifolius cv. Jadia local) and cluster bean (Cyamopsis tetragonoloba cv. Durgapura safed) were sown in 4 m X 3 m plots on 13 July 1980 and 22 July 1981. Superphosphate and muriate of potash were applied to supply 60 kg P2Os ha -1 and 40 kg K20 ha -1, respectively. F o r t y days after sowing, ten plants from each treatment were dug out and their fresh and dry weights determined for dry matter production and plant water status. Leaf area of the samples was determined with an automatic area meter model No AAC-400 of Hayashi Denkoh Co. Ltd. Tokyo, Japan. Roots of the dug out plants were taken out by carefully washing them with a water jet. The fresh and dry weights of the roots and nodules were determined. Periodic soil moisture was determined at different depths using a Troxler neutron probe. Maximum soil temperature in the root zone (10 cm depth) was recorded at weekly intervals with the help of an Aplab telethermometer. The crops were harvested on 8 October 1980 and 24 October 1981. Then the grain and dry matter yields of the crops and weeds were determined.

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Fig. 1. Cumulative open pan evaporation a n d rainfall during the growth period.

377 RESULTS AND DISCUSSION

During the growing seasons the total rainfall in 1 9 8 0 was 160 mm and in 1981 230 mm (Fig. 1). Though the rainfall during 1981 was higher, its distribution was less favourable. Most of it fell in September and the crops experienced moisture stress during the active growing phase. In 1980, however, most rain occurred during July and early August. Cumulative pan evaporation was higher in 1 9 8 0 than in 1981 and the range was 700 mm to 6 5 0 ram, respectively.

Soil temperature Soil temperature at 10 cm depth was generally higher during 1981 than 1 9 8 0 (Fig. 2). With increasing amounts of mulch there was a decrease 56

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378 in maximum temperature in the soil. The differences in temperature were, however, only higher up to 6 t ha -1 . The differences in soil temperature between mulched and unmulched plots were more pronounced during dry periods than during wet periods. In 1980 soil temperatures ranged from 29 to 47°C whereas in 1981 they ranged from 29 to 54°C. Thus in 1981 the soil temperature was about 7°C higher than in 1980. An occasional steep drop in soil temperature during the crop growth period was due to cooling caused by rainfall. Higher temperatures experienced in the r o o t zone by the crop during 1981 seems to be an important factor for adversely affecting root and shoot growth and the yield of the crops. Philpotts (1967) reported a 6 - 8 ° C decrease in maximum soil temperature with 2.5 cm thick straw mulch which increased the nodulation and dry matter yield of cowpeas. R o o t grow th

Greater applications of grass mulch improved the root growth as is evident from the increase in root weight, root length and the nodule weight, o

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Fig. 3. R o o t growth as affected by different rates of grass mulch application.

379

particularly of green gram and cluster bean (Fig. 3). For dew gram, however, no significant differences were found. The general increase in root growth was observed up to 9 t ha -1 of mulching material. There were no significant differences in root weight and nodule weight of green gram and cluster bean but under similar conditions the weights of dew gram were significantly less. The differences in root length of the crops were more conspicuous than the root weights. R o o t growth of green gram was generally higher than for cluster bean and dew gram. Shoot growth and plant water status Mulch application increased the growth of the plants. There was increase in leaf area, the height and the weight of the plants at the active growing stage (40 days after sowing) of the crop (Fig. 4). The general response ,Green gram 500

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380

was, however, up to 9 t ha -1 of mulch application, The response of green gram to mulch application was generally higher than that of cluster bean and dew gram. Leaf water content in the mulched plots was higher than in the unmulched plots particularly during the period of severe drought. It was highest in dew gram followed by that of green gram and cluster bean. While dew gram and green gram plants were fully turgid, there was a temporary wilting in cluster bean showing the sensitiveness of this crop to moisture stress. The crop seemed to have a special mechanism to escape the harmful effects of drought and quickly regained turgidity when favourable moisture conditions were restored after rainfall. Philpotts (1967) and Masefield (1957) also reported an increase in root growth, nodule weight and dry matter production of cowpeas with the use of grass or straw mulch.

Weed growth With increasing amounts of mulching materials there was a reduction in dry matter yield of weeds (Fig. 5). Weed production was significantly higher in 1981 than in 1980. This was probably due to the drier conditions in 1981 which suppressed the crop growth and provided favourable conditions for a better growth of weeds. Weed growth in green gram crop was higher than in dew gram and cluster bean. Mulch application, in general, suppressed the growth and reduced the population of weeds. The reduced crop-weed competition was, thus, another important factor which increased crop production in mulched plots.

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Fig. 5. Weed yield as affected by different rates of grass mulch application.

381

Dry matter production and grain yield of crops The use of grass mulch increased the dry matter and grain yield of green gram, dew gram, and cluster bean (Table I). The general response was, however, up to 9 t ha-' level of grass mulch application. Higher amount of mulch application was not useful in further increasing the yield of crops. On the contrary, in certain cases it decreased yields. This might be due to delay in the maturity of the crops (Anderson and Russel, 1964). The dry matter production and grain yield of cluster bean was highest followed by green gram and dew gram. During the favourable year 1980, low levels of mulch were found more useful than the higher ones. On the other hand TABLE I E f f e c t of different rotes of grass m u l c h a p p l i c a t i o n o n the g r o w t h and y i e l d o f legumes

R a t e s of grass m u l c h application (t h a -~)

0 3 6 9 12 LSD (P~0.05)

1 9 8 1 Dry m a t t e r y i e l d (q h a " t )

Grain y i e l d ( q h a -a)

Green gram

Green g r a m

D e w gram

Cluster bean

1981

1980

1981

1980

1981

1980

0.4 2.3 3.5 4.9 5.6 1.5

2.4 3.5 4.4 4.89 3.6 0.6

1.7 2.9 4.1 5.2 4.1 2.1

2.6 3.1 3.9 3.3 2.9 0.3

6.2 6.2 6.5 7.3 8.9 NS

5.1 5.4 6.5 6.0 5.6 0.5

1.7 6.4 10.6 14.8 16.4 3.5

Dew gram

5.5 7.5 11.2 13.5 11.1 3.7

Cluster bean

12.1 10.3 16.6 18.0 17.7 NS

T A B L E II E f f e c t of different rotes o f grass m u l c h application o n w a t e r use and w a t e r use e f f i c i e n c y o f the crops

Rates of grass m u l c h application (t h a -4 )

Water use e f f i c i e n c y (kg grains m m "4 h a ~ ) G r e e n gram 1980

0 3 6 9 12

1.82 2.67 3.46 4.00 2.79

D e w gram 1981

(132) (131) (127) (120) (129)

0.24 1.54 2.27 3.20 3.37

1980

(168) (149) (154) (153) (166)

1.76 2.26 2.65 2.34 2.18

Cluster b e a n 1981

(148) (137) (147) (141) (133)

0.86 1.56 2.27 2.68 2.46

1980

(198) (186) (181) (194) (167)

Figures in parenthesis indicate water use of the crop.

3.59 3.67 4.81 4.65 3.78

1981

(142) (147) (135) (129) (148)

3.48 3.25 3.71 4.22 4.59

(178) (191) (175) (173) (194)

382 higher levels o f m u l c h were f o u n d m o r e beneficial d u r i n g the d r y y e a r o f 1981. In general, c r o p r e s p o n s e t o m u l c h a p p l i c a t i o n was m o r e p r o m i n e n t during 1981 w h e n t h e r e was a severe d r o u g h t during early p e r i o d o f c r o p g r o w t h . This c o u l d be d u e to a m o r e f a v o u r a b l e soil e n v i r o n m e n t p r o v i d e d b y the m u l c h ( V a n Wijk et al., 1 9 5 9 ; F r i t s c h e n and S h a w , 1 9 6 0 ; A d a m s , 1 9 6 2 ; M o o d y e t al., 1 9 6 3 ; Bansal e t al., 1971). Water use e f f i c i e n c y o f t h e c r o p increased w i t h levels o f m u l c h applic a t i o n p a r t i c u l a r l y u p t o 9 t h a -1 t h o u g h t h e r e w e r e no significant differences in w a t e r use b y the c r o p (Table II). G e n e r a l l y higher w a t e r use was o b s e r v e d u n d e r u n m u l c h e d r a t h e r t h a n u n d e r m u l c h e d c o n d i t i o n s . This was d u e t o u n p r o d u c t i v e losses b y e v a p o r a t i o n a n d w a t e r used b y weeds. Water use e f f i c i e n c y o f t h e c r o p s was, t h e r e f o r e , l o w e s t in u n m u l c h e d c o n d i t i o n s . Water use b y the crops was o b s e r v e d t o be higher in 1981 t h a n in 1 9 8 0 leading to a higher w a t e r use e f f i c i e n c y in 1 9 8 0 t h a n 1981. Water use e f f i c i e n c y o f cluster b e a n was the highest f o l l o w e d b y t h a t o f green g r a m a n d d e w gram. F r o m these results it can be c o n c l u d e d t h a t grass can be a d v a n t a g e o u s l y used as m u l c h i n g m a t e r i a l f o r i m p r o v i n g soil e n v i r o n m e n t a n d the prod u c t i o n o f legumes. ACKNOWLEDGEMENTS T h e a u t h o r s wish to t h a n k the H e a d o f t h e Division o f Soil-Water-Plant R e l a t i o n s h i p a n d t h e D i r e c t o r , C A Z R I , J o d h p u r f o r p r o v i d i n g t h e necessary facilities f o r this study.

REFERENCES Adams, J.E., 1962. Effect of soil temperature on growth of sorghum and yield. Agron. J., 54: 257--262. Anderson, D.T. and Russel, G.C., 1964. Effect of various quantities of straw mulch on the growth and yield of spring and winter wheat. Can. J. Soil Sci., 44: 109--118. Bansal, S.P., Gajri, P.R. and Prihar, S.S., 1971. Effect of mulches on water conservation, soil temperature and growth of maize (Zea rnays L.) and pearl millet (Pennisetum typhoides). Indian J. Agrie. Sci., 41 : 467--473. Fritschen, L.J. and Shaw, R.H., 1960. Effect of plastic mulch on micro climate and plant growth. Iowa State Coll. J. Sci., 35: 59--71. Gupta, J.P., 1978. Evaporation from a sandy soil under mulches. Ann. Arid Zone, 17 (3): 287--290. Gupta, J.P., 1980. Effect of mulches on moisture and thermal regimes of soil and yield of pearl millet. Ann. Arid Zone, 19: 132--138. Gupta, J.P. and Gupta, G.N., 1982. Effect of mulches on hydrothermal environment of soil and crop production in arid zone of Western Rajasthan. Paper presented at the 12th International Congress of Soil Science, held at New Delhi, Feb. 8--16, 1982.

Masefield, G.B., 1957. The nodulation o f annual leguminous crops in Malaya. Emp. J. Exp. Agric., 25: 139-150.

383 Moody, J.E., Jones, J.N. and Liliard, J.H., 1963. Influence of straw mulch on soil moisture, soil temperature and growth of corn. Proc. Am. Soc. Soil Sci., 27 (6): 700--703. Philpotts, H., 1967. The effect of soil temperature on nodulation of cowpeas (Vigna sinensis). Aust. J. Exp. Agric. Anim. Husb., 7: 372--376. Van Wijk, W.R., Larson, W.I. and Burrows, W.C., 1959. Soil temperature and early growth of corn for mulched and unmulched soils. Proc. Am. Soc. Soil. Sci., 23: 428--434.