Impact of Neem (azadirachta indica a. juss) Plantation under Agroforestry system on soil properties in semi-arid region of India:

A.K. Pandey, K.R. Solanki and V.K. Gupta
Indian Grassland and Fodder Research Institute, Jhansi - 284 003

INTRODUCTION

Intensive farming leads to the reduction of soil fertility which is menace globally for productivity of agricultural crops and sustainable development on long term basis (Young, 1989). In last three decades, incorporation of trees in the farm lands is well recognized under agroforestry systems for maintaining of soil fertility and productivity (Kamara and Haque, 1992; Singh et. al., 1989). The main effect of the trees on soil properties are above ground organic matter inputs through litter fall decomposition and thus improves nutrient cycling (Sanchez et. al., 1985). Inspite of various information available on different aspects of neem trees little information is available on its effect on soil properties. Present investigation provides information on the impact of neem trees on soil properties in semi-arid region.

MATERIALS AND METHODS

The experiment was initiated in 8 year and 4 year old neem plantations at two separate sites at Central Research Farm of National Research Centre for Agroforestry, Jhansi is situated between latitude 24º 11`-26º 27`N and longitude 78º 17` - 81º 34`E at about 275 m above mean sea level. Trees were planted in July 1989 at site-1 at spacing of 5 x 5 m while at site-2 plantation was done in July 1994 at a distance of 4 x 4 m. Fifty-four trees in six replications each of nine trees in 3 x 3 m orientation selected for soil sampling under the trees. The soil of 4 year stand was sandy clay loam in texture while soil of 8 year stand was red (Rakar) having very light texture and low water retention capacity. in Kharif season, urd (Phaseolous mungo) was sown as under storey crop in 8-year-old plantation and gram (Cicer arietinum L) as Rabi season crop under 4-year-old plantation consequently for three years. These crops were also sown out side of neem plantation as a control. The soil samples were collected in all six replications in both plantations at 50, 100, 150 and 200cm distances in both sides from centre line of the tree from 0-15 and 15-30 cm soil depth in beginning of experiment (initial) and after 3 years at closing of experiment (final) under the trees and in open site where crop alone was grown (control). The samples were taken from the surface of freshly dug pits by Gainti and collected in polythene bag. The collected soil samples were analyzed to estimate pH by pH meter at 1:2.5 soil water ratio, organic carbon (Jackson, 1073), available nitrogen (Subbiah and Asija, 1956), available phosphorus (Olsen et al., 1954) and available potassium (Piper, 1966).

RESULTS AND DISCUSSION

The findings of present investigation showed that top soil under the trees contained higher level of organic carbon compared to soil in nearby open field. The organic carbon (%) was higher by 0.11 and 0.12 (percentage increase was 22 and 26, respectively) under tree canopy after three years in 4 and 8 year old plantations, respectively in top soil (0-15 cm) while this difference was only 0.03 and 0.02 respectively for the same in control. The significant differences observed in organic carbon status of soil under both plantations over control indicated that contribution of litter and by products of trees improved the fertility status of soil. Since about 20-25% of total living biomass of tree is in roots (Armson, 1971) and there is constant addition of organic matter to the soil through decaying of dead roots, that lead to improvement in carbon status of soil (Balkrishnan and Toky, 1993; Young, 1989). Pandey et al., (2001) reported that annual addition of 2976 kg ha–¹ and 6060 kg ha–¹ litter in 4 year and 8-year old neem plantation respectively in semi-arid region. The values for organic carbon observed at various distances from tree based demonstrated a significant decline in organic carbon with the increase in distance from the tree base under both the plantations. This might be due to the fact that more and more litter got accumulated near tree base with advancement of growth. These results are in confirmity with that reported by Kamara and Haque (1992); Vadi Raj and Rudrappa (1990); Rao et al., (2000). Organic carbon status at various soil depths suggested that appreciable decline in organic carbon as the soil depths increased (Singh et al., 1989: Rao et al., 2000).

SOIL pH
The pH of the soil in both the plantations decreased over the control. The mean value for soil pH after the termination of experiment under the tree canopy decreased by 0.28 and 0.34 in 0-15 cm soil depth over initial value in 4 and 8 year old plantations, respectively. The soil pH in 15-30 cm depth was decreased by 0.20 and 0.21 respectively which was less than 0-15 cm depth under tree canopy. This decrease may be attributed to litter fall, which on decomposition is known to produce weak acids. Hesselman (1962), Lutz and Chandler (1957) reported that the forest floor favoured the decomposition of organic mineral cycling. Reducing in soil pH under tree canopy have been well advocated by several workers (Agarwal, 1980; Vadi Raj and Rudrapa, 1980).

NITROGEN
The content of available nitrogen was significantly higher under the tree canopy as compared to control (without trees) in both the plantations of neem. The nitrogen content was higher 38-90 kg ha–¹ and 35.75 kg ha–¹ under the tree canopy over control at the closing of experiment in 4 year and 8 year old neem plantation, respectively. Increase in nitrogen level during three years was 19.41 kg ha–¹ and 37.56 kg ha–¹ in top soil (0-15cm) in 4 year and 8 year old plantations respectively. While difference was only 5.10 kg ha–¹ and 10.25 kg ha–¹, respectively in control (without trees). Neem litter accumulation around the trees might be the main source for potential build up of nitrogen above those outside the trees. The increase in nutrients under neem trees over the control was attributed largely to the nutrients in the litter. Pandey et al., (2001) reported that annual nitrogen addition by litter in 4 year and 8 year old plantation was 50.05 kg ha–¹ and 98.02 kg ha–¹, respectively. Increase in available nitrogen content of soil under different tree species have been reported by several workers (Singh et al., 1989; Puri et al., 1994; Bheemaigh et al., 1995). Available nitrogen was less at 15-30 cm soil depth than 0-15 cm which further confirmed litter add nutrients to the soil by the process of decomposition.

PHOSPHORUS
Increase of available phosphorus content of soil under tree canopy was 5.14 kg ha–¹ and 3.96 kg ha–¹ in 0-15 cm soil depth as compared to control (without trees) in 4 year and 8 year old plantation, respectively. Phosphorus level increased after three years under same plantations was 2.41 kg ha–¹ and 2.32 kg ha–¹, respectively which was quite higher as compared to control. This can be attributed to solublizing behaviour of organic acids that are related into soil during organic matter decomposition (Rao et al., 2000; Shankarnarayan, 1984). Soil organic phosphorus is one of the supplying source of available phosphrous (Zenggjiang et al., 1995). As soil organic carbon increased, the organic phosphorus was correspondingly increased. Neem trees have contributed substantial amount of available phosphorus to soil over a period of time reported by other workers also (Vadi Raj and Rudrappa, 1990; Rao et al., 2000). Phosphorus added by litter in 4 year and 8 year old plantations was 1.105 kg ha–¹ yr–¹ and 2.245 kg ha–¹yr–¹, respectively (Pandey et al., 2001).

POTASSIUM
The available potassium content of soil was observed significantly higher under tree canopy as compared to control in both the neem plantations. This may associated with litter accumulation at around the trees, which was the main source for potential nutrients build up above those outside the trees. The increase in nutrients under neem tree canopy over the controls attributed largely to the potassium content in the litter. Pandey et al., (2001) reported that potassium added by litter in 4 year and 8 year old plantation was 13.8 kg ha–¹yr–¹ and 32.02 kg ha–¹yr–¹, respectively. The closed canopy structure in both the plantations have prevented potassium from leaching down the profile during rainy season, thereby showing higher values kg ha–¹ at the 0-15 cm depth of the soil (62.55, 67.55) than at 15-30 cm soil depth (48.66, 46.65) in 4 and 8 year plantation, respectively. Such observation was earlier recorded by other workers also (Shankarnarayan, 1984; Kapoor and Singh, 1992; Agarwal, 1980; Singh et al., 1989; Puri et al., 1994; Rao et al., 2000).

Source: Indian Journal of Agroforestry

NAMES OF NEEM IN DIFFERENT LANGUAGES

Hindi: nim, nimb,ninb,balnimb, neem, nimgachh

Marathi: nimbay, balantanimba, kadukhajur, lumb, limba, limbachajhada, nib

Bengali: Nim, Nimgachh

Gujarati: Leemdo

Kannada: bevu, bevina mara, bemu, kahi bevu, kaybevu, kaypebivu, nimba, olle-bevu, vevina

Malayalam: veppu, aryaveppu, aria-bepou, ariya-veppa, aruveppu, arytikta, kaippanveppu, nimbam, pisumarddam, rajaveppu, veppa, veppuu

Tamil: vembu, vempu, veppam, veppamaram, veppu, acutakimaram, akaluti, akappalamakkiyacatti, akuluti, ammapattini, ammapattiri, aracankanni, aricu, aristakam, aritam, arukkapatavam, arulaci, arulundi kaduppagai, arulupati, aruluruti, arunati, aruttakam, aruttam, atipam, cakarakam, cakatam, cakatamaram, cakatamuli, cankumaru, cankumarutam, cankumarutamaram, carutopattiri, carvacatakam, catapalacitti, catapalacittimaram, cavamuli, cankumaru, cippuratimuli, cirilipannan, cirinapannam, cirinapanni, cirinapannimaram, cirinapattiram, cirnaparam, cirnapattiram, civam, civamatukam, civamatukamaram, iravippiriyam, kacappi, kacappu, kaitariyam, katippakai, kecamutti, kinci, kincika, kinji, malakai, malakam, malugam, malukam, maturakkacappi, mutikam, naiatampumaram, nattuvempu, nim, nimpakam, nimpamaram, nimpataru, ninpam, niriyacam, niriyasam, nitarpam, niyacam, niyamanam, niyamanamaram, niyaracam, niyaratam, niyatam, pacumantam, paripattiram, pariyam, parvatam, perunimpam, picaram, picumantam, picumantam, picumattam, pirapattiram, pisidam, piyacukam, puyari, puyarikam, sengumaru, tittai, tuttai, ukkirakantam, ukkirakanti, ukkragandam, varuttam, vempumaram, venipam, vepa, veppan, vicimikini, vicumantam, vicumikini, vicumini, viruttamaram, visapatcani

Telugu: vepa, nimbamu, vemu, yapa, taruka, vepa-chettu, yeppa

Urdu: neem, burg neem, gul neem, maghz tukhm-e-neem, neem ke khusk pattay, neem ki namontian, poast darakht neem, poast darakht nim, poast neem, roghan neem

French: Azarirae d'lnde, Margousier

German: Indischer Zedrach

Persian: azad-darakhte-hind, azaddarachte-hind, neeb

Arabic: Azad Darkhtu Hind

Burmese: Tamabin, Kamakha

Latin: Azadirachta indica A. Juss, Melia azadirachta Linn

Singapore: Kohumba, nimba

Indonesia: Mindi

Nigeria: Don goyaro

Spanish: Margosa

Nepal: Nim

Portugese: Margosa, Nimbo

Tibetan: ni mbal, ni-mba