To study the N response of sorghum (Sorghum bicolor) intercropped with pigeon pea (Cajanus cajan), 3 experiments were conducted in Vertisols. In experiment 1, sole sorghum (180 000 plant/ha), sole pigeon pea (40 000 plants/ha) and 3 intercrop population treatments (40: 40, 80: 80 and 120: 120% of sole optimum) were sown as main plots with 4 levels of N (0, 40, 80 and 120 kg/ha) only to sorghum as subplots. It is concluded that intercropped and sole sorghum responded similarly to applied N. Different sorghum populations in the intercrop performed similarly. Pigeon pea did not seem to be contributing any N to its companion sorghum. Sorghum at higher N levels had a greater effect on pigeon pea yield. Both crops did equally well at 45 cm and 90 cm when grown as sole crop

Rego, T J

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SMIC DOCUMENT SORGHUM AND MILLETS INFORMATION CENTER International Crops Research Institute for the Semi-Arid Tropics ICRISAT Patancheru P.O. Andhra Pradesh, India 502 324 Nitrogen Response Studies of lntercropped Sorghum with Pigeonpea Abstract To study the N response of intercropped sorghum with p~geonpea, three experiments were conducted during 1977 and 1978 in Vernsols at ICRISA T Center In Experiment 1, so esorghum 1180 000plants ha), solepigeonpea 140 OOOplants hha and three Intercrop populat~on treatments 140 40.80 80 and 120 120% ofsoleoptimumi weresownas main plots with four levels of N 10, 40, 80, and 120 kg ha1 only to sorghum as subplots In Ekperiment I/, sole sorghum at optimum plantpopulation 1180 000plants ha1 ~ntercrop sorghum at 33,67, and 100% ophmum populaoon with constant pigeonpea population 140 000 plants ha) with the same levels of N as fn Experiment I, and sole pigeonpea (40 WOplantsihal were grown in a randornued bloc. iesiqn In Experiment 111, a constant sorghum 1150 000plants ha1 andpigeonpea popuidtion 140 00Oplants ha/ were planted as sole crops at 45 and 90 cm and as Intercrops fn  allernale rows at 45 cm with three levels of N 10, 60, and '20 kg ha/ applied only to sorghum in a rdndomired block desfgn In ~7llthree xperiments sorghum variety CSH Gandpigeonpea ICRISAT I weregrown Based on the results of these experiments it can be concluded that intercropped and sole sorghum responded similarly to applied N Different sorghum populations fn  the frltercrop performed similarly Pigeonpea d ~ d  nor seem lo be contributing any N to  its companion sorghum Sorghum at higher N levels had a greater effect on plgeonpea yleld Sorghum as wellas pigeonpea didequally wellat45cm and90 cm when grown as sole crops lntercropping of a nonlegurne with a legume crop is a common practlce among the semi-arid tropics (SAT) farmers of India. In a subsistence farming sltuatlon wi th uncertain and erratic ra~nfall, which is characteristic of the SAT reg- ion, vew Ilfileanentlon has been paid in thepast to Improving the soil productivity Even though N is the mosr l~rn~t lng plant nutrient in these soils, intercropped legumes mlght have been responsible for rnalntain~ng soil productiv~ty, at least at a subsistence level. Meager data are ava~lable on the response of a nonlegurne to N in the presence of a legume. Enyl (19731 re- ported an lntercrop system where malze and other legumes were grown, crops such as bean or cowpea had a more adverse effect on malze grain y~eld than did plgeonpea. He att~ibuted this to the hlgh rates of nutrient absorption by those two legumes, which coincided with that of the malze crop, whereas pigeonpea had the greatest nutrient demand after the harvest of malze. For the experlrnents described here, a typical sorghum,pigeonpea intercrop system was chosen to compare the N response to  lntercropped and sole-crop sorghum. Materials and Methods Fteld experiments were conducted-in 1977 and 1978 during the kharif (mofisoon) season on a med~um-deep Vertlsol at ICRISAT Center under ra~nfed cond~llons These soils are low in or- ganic matter, ava~lable N, and available P ,  but hlgh In exchangeable K .  The dominant clay mineral is montrnor~llionite The physical com- position of thesotls and the initial fertility status of the experimental sites are given in Table 1. The total amount of ra~nfall during the 1977 Tabla 1. Soma physlul and chmmlul charactmrisdcs of modlum-dmpth Ve~tltols m ICRISAT e m u .  - Depth Org C pH CEC Gravel C sand F sand S!lc Clay lcm) 1%) ,me lOOgl General characrer~sf~cs 0-155 0 30 8 3 43 8 3 11 3 13 7 17 7 57 3 Depth Avarlable N Ava~lable P Exchangeable U I C ~ )  I D P ~ )  ( P P ~ I  I P P ~ )  S p ~ t h c  haracrertsr,cs Exper mental 9118 I 0-30 79 6 5 195 Exper nental site II 0-30 62 7 0 144 Exper mental site Ill 0-30 8 1 5 3 168 growing period was 571 mm, which was below normal but well distributed. However, during the 1978 growlng per~od, the total amount of ramfall exceeded the average rainfall (7151 by 373 mm. During 1978 there were many contlnu- ous ralny days, resulting In short periods of temporary waterlogging. Experiment l In 1977, a 5 y 4 spl~t-plot design of five popula- tions :100:0,0~100.40:40,80:80, and 120:120% of sorghum and pigeonpea sole optimum plant population, consider~ng 180 000 and 40 000 placed by the s~de of sorghum rows as men- t~oned earl~er at 28 days after germmation The subplot had 12 rows of 9-m length 15 4 x  9 ml. Thecentral four rows of sorghum and two rows of plgeonpea were harvested at maturity. Our. ing the entire growlng period, only two hand weedings were glven, one In the second week after planting and one in the f ~ f t h  week. A research level of plant protection was given against shoot fly and stemborer of sorghum and against pod borer of plgeonpea. Sorghum was harvested after 96 days and plgeonpea was harvested after 158 days. plants as optimum for sole sorghum and DloeonDea, res~ectivelv) as main o~ots and four Experiment I' 7 - - ~  ie;els of N 10, 40, 80, and 120 kg Nha applied only to sorghum) as subplots were replicated four times. These varying populations were chosen because earlier evidence showed that the intercrop responded to increasing popula. tlons and there is a l~kelihood of interaction between populations and N levels. Before land preparation, 20 kg P:ha was un~formly broad- cast and incorporated. Sorghum cultivar CSH-6 and pigeonpea ICRISAT-1 were planted manu- ally in 45-cm rows, both in the sole as well as in the lntercrop A 2.1 sorghum pigeonpea row- plantlng pattern was followed for the inter- crops, and varying plant populations were achieved by changing the intrarow spacing Both crops were sown at a higher than normal (5-6timesl seed rate and thlnned to thedesired In 1978, a similar trial wasconducted with slight modificat~ons based on the results of experi- ment I. There were 17 treatments in all, repli- cated threetimes In a randomized block design. The treatments consisted of one sole sorghum at optimum population (180 000 plantsiha) plus three sorghum!pigeonpea intercrops (at 33.100, 67:100, and 100:100% of optimum populations in a 2: 1 row proportion) with four levels of N (0, 40.80, and 120 kglha) applied only to sorghum, and onesole pigeonpea at optimum population 140 000 plants.ha) Land preparation, P fertiliza- tion, and other operations were similar to those of Experiment I, but planting was don% by a seed d r~ l l  At the time of writing, enly sorghum had been harvested (after 98 days). piant population 14 days after germination. ~~~~~i~~~~ 111 . After f~nal thinning (and exceptforzero N plotsl. 20 kg N ha as ammonium sulfate was placed by During 1977, another sorghumipigeonpea thesideofsorghumrowsabou110cmaway and lntercrop experiment was conducted with a about 5 cm deep: the remaining N. as urea. was constant population of 150 000 sorghum plantdha and 40 000 plgeonpea plants ha in a ghum and plgmnpea were hawesled 95 and 1: 1 row pattern in 45-cm rows In addlt~on, both 159 days after sowing, respect~vely. crops were grown as sole crops In 45. and 90-cm rows but keeplng the population constant ~ ~ ~ , , ( t ~  and ~ i ~ ~ ~ ~ ~ ; ~ ~  These plantlng panerns were tr~ed w ~ t h  three levels of N (0 60 and 120 kg ha1 appl~ed only to sorghum These nine treatments were repl~. cated four tlrnes In a randorn~zed block design Experiment I The planrtng was done manually and all other There was a slgnlficant gratn y~eld response of operations were done as in Experlrnent I Sor sorghum (Fig 1) to N up to80 kg N ha, whereas yields at 80 kg and 120 kg N.ha were similar Interestingly, in the intercrop sltuatlon, all three populations performed equally well and thelr grain yields dld not s~gnificantly differ from each other However, sole sorghum yielded moregrain yield than Intercropsorghum at any level of N and more so at higher levels of N. On an average, the intercrop yleld was nearly 20% less than the sole The lnteractlon belween population and N ievelswas not significant. The increase In grain yield with increasing N levels was mainly due to an Increase in grain welgho ear and an Increase In 1000-grain weight. whereas, as the population increased, gram weightiear decreased, especially from 80 to 120% populatlon. This character might have been responsible for compensation of yields of different sorghum populations. The response of sorghum populations at different levels of N (Fig. 2 )  reveals that near- optimum sorghum populations (80 or 120% of optimum) behave more or less as soleoptimum populatlon, although at a lower grain yield level: but low population (40% of optimum) at hlgher hr (120 kgrhal still responds to N. The sorghum fodder yield also more or less fol- lowed the same trend. except that the fodde~ ylelds at different populations did not d~ffel slgnlficantly The pigeonpea grain as well as stalk yields ir the lntercrop were not Influenced by either thc N applied to its companion sorghum or b j  varylng populations. Even though a reductior In the plgeonpea yield might be expected espec~ally at higher levels of N and at h~ghel sorghum populat~on, these effects mlght have been countered by simultaneous Increase ir plgeonpea population The Cropping System! group at ICRISAT, on similar soil and dur~ng thc same perlod working in 2.1 sorghum plgeonpea intercrop system, found a positlvr response to plgeonpea population whereas sorghum populations at 90 000 and 360 00C plantsiha performed equally well (ICRISAl 1978). On an average, pigeonpea yields were about 65% of the sole pigeonpea graln yield! and about 60% of stalk y~elds. The total N uptake (Fig. 3) in sorghum in. creased with increasing levels of applied N. Or an average, sole and all intercrop populations were similar in N uptake. The different levels 01 N applied to sorghum in intercrop did no1 influencetheN uptake by plgeonpea. Thetotal F uptake by sorghum was simllar for the 40, 80 and 120 kg Niha treatments, but this was highel than zero N treatment As i n  the case of h uptake, the total P uptake by pigeonpea was no! influenced by different N levels. C - /<L - - 9-\ Experiment II - Only the sorghum crop in thls experiment has , , been harvested, and the data are oresenled IF i3ixoAy ,'/ Table and the 2 Intercrop Unl~ke the sorghum prev~ous responded year both up the to sole 12Csorqn~rn papuiar on5 kg Niha Thls may be mainly because of excess / 2MXI ,I - >1C 120 ram resulting In more N loss compared to the .---- do 60 previous year Thesorghum In lntercrop was as - - 80 80 good as sole In 0 and 40 kg N ha, but at 80 and 100 0 120 kg Nlha it ylelded about 90% of solBsor lwo i ghum Durlng theprevlous year, a kmllar trend L- --r- had also been observed 40 BU 110 Nlroorn  900 csl  on k g  ha Experiment 111 F~gure 2 Nttrogen response of solesorghum and different populartons of sor There was no s~gnlflcant dtfference In sorghum ghum tntercropped wtth ptgeonpea graln yleld between 4 5  and 90-cm row spacing on Vemsols at ICRISAT Center, as a sole crop at all levels of N (Table 3) Thc 1977 sorghum gram ylelds both In sole as well as In hyure 3 Effect of n~trogen on the total N uptake of ~ntercropped sorghum and plgeonpea grown on Vertlsols at ICRISAT Center, 1977. lntercrop responded up to 120 kg N:ha. The intercropped sorghum ylelded s~gnif~cantly lower grain when compared to sole cropplng at 60 and 120 kg N:ha, but they were not slgnific- antly different at zero N treatment. The increase In grain y~eld of sorghum w ~ t h  increase in N level is mainly due to Increase in grain we~ghti ear and increase in 1000-gram we~ght The reduction in intercrop sorghum gram yield compared to sole at the same level of N 1s mainly due to reduction in grain weightear Pigeonpea grain yields from 45- and 90-cm row spacings were similar. The pigeonpea yields were significantly lower in intercropping than in sole cropping. The different levels of N appiied to companion sorghum did not influ- ence the intercrop pigeonpea, slnce pigeonpea yields were slmllar a1 d~fferent N levels. The advantages of intercropping were 68, 39. and 47% for the 0, 60, and 120 N treatments, respectively Th~s may be In agreement with the work of L~boon and Hawood 119751, but in the 2 1 system of Experimentl. the LER was more or less the same at all levels of N-1 46, 1 58, 1 34, and 1 41 at 0. 40. 80. and 120 kg N ha, respect~vely. Although the LERs for the 60 and 120 N tredtments were lower thdn the zero N treatment, the total absolute yield or total value was far greater in the 60 and 120 N treatments. The data for fodder y~elds of sorghum and stalk yields of pigeonpea show a pattern similar to that of their graln yields The total N uptake by sorghum (Fig 41 shows that at 0 and 60 kg Ntha. the sole and lntercrop sorghum were similar. but at 120 kg N'ha, the intercrop sorghum had a lower uptake than the sole As expected, with increas~ng levels of N, the N uptake of sorghum also increased In contrast, plgeonpea at all three levels of N to sorghum had more or less the same amount of N uptake This emphasizes that whether 11s companion sorghum is fer- tilized w ~ t h  N or not, the uptakeremalns moreor less constant Dalal (19741 had clearly shown that In a maize~pigeonpea alternate-row ar- rangement, ar the end of rnaize harvest 116 weeks), the intercrop piyeonpea had taken only 5 7 kg N, whereas the sole pigeonpea had taken 17 1 kg N,ha. At pigeonpea harvest, however, sole arrd lntercrop plgeonpea had taken 119 4 and 126 8 kg N ha. respectively. which was slm~lar In Dalal's trial, sole and ~ntercropped pigeonpea yielded similarly, but intercropped maize yielded only 80% of sole maize From the data of sorghum-N uptake at the zero N level, it can be concluded that there was no current transfer of N from ltitercrop pigeonpea to sor- ghum as sole, and intercrop sorghum had almost the same quantity of N upt+e. There was also no evidenceof transfer at a low fertility level of 60 kg N. Henreli and Valiis 11977). in an extenswe review on transfer of N in grass1 legume forages, found no evidence of current transfer of N from legume to its companion nonlegume. Dalal and Quilt 119771, in a study of response of pigeonpea to N, clearly showed that pigeonpea did not respond to applied N. This response holds here also. because even though plgeonpea did not receive d~rectly any ~ e b l e  2. Effocta of nhmgmn end populnion on gran vietd (kg/h)  of wrghum (Erporimont W 19781. Populafton 1% of sole optmum) Sole crop Intercrop Applied N 100 0 33 100 67 100 100 100 Mean 0 1293 1621 1394 2082 1598 40 3192 3542 3268 2986 3252 80 4293 4261 3920 3944 4104 120 4967 4593 4656 44Aa 4666 Mean 3436 3504 3374 3365 Population N Population x N LSD 10.05) NS 298 NS cv I%) 1 0 5  Table 3. E f f ~ e t a  ot row spmolng end nh-n eppIiwtIm upon gnin ~d atnw/mteik ykId8 ot sdm and intorcroppod sorghum mnd plgwnpme (Expmrlment Ill). Crop 0 N on sorghum 60 N on sorghum 120 N on sorghum Rowspacing Y~eld LEA Yleld LER Y~eld LER (cm) ikgrhal Ikg'ha) lkg'ha) Drain yteld Sole sorghum 45 Sole sorghum 90 Sole pigeonpea 45 Sole pigeonpea 90 lntercropped sorghum Infercropped plgeonpea Total LER LSO I0 0s) Sotghum 571 Ptgeonpaa 401 CV 1%) Sorghum 14 3 Plgeonpsa 22 9 Straw stalk yield Sole sorghum 45 4110 5640 6750 Sole sorghum 90 4110 4390 5360 Sole pageonpea 45 2740 Sole plgeonpea 90 2440 Intercropped sorghum 3420 0 83 4 2 M  0 05 4690 0 77 Intercropped pgeonpea 1760 0 6 8  1440 0 5 6  1900 0 7 4  - - - Total LER 151 1 4 1  - 1 5 1  .SO I0 051 Sorghum 770 Plgeonpea 111 C V i h l  Sorghum 11 1 Pigeonpea 33 6 .r Alier-ate row 45 crn Figure 4. Effect of nitrogen on total N uptake of sole and intercropped sorghum andpigeonpea grown on Vertisols at ICRISAT Center, 1977. applied N, itscompanion sorghum received up to 120 kg Nlha. The total P uptake more or less followed the same pattern as N uptake but at a very low magnitude. Conclusions Based on the results of these experiments, the following conclusions can be drawn. In a sorghumlpigeonpea intercrop system, the sorghum response to applied N is more or less similar to solbsorghbm response. The sorghum crop seems to be very plastic with regard to population response. At high levelsof N (80or 120 kglha), there is a slight reduction in sorghum LEA, which causes a small reduction in total LER. Indirect evidence reveals that pigeonpea in a 2:l sorghumlpigeonpea system may suffer a little at higher levelsof N applied to its compan- ion sorghum, and in such a situation, a re- sponse to pigeonpea population might be ex- pected. At low levels of N fertility, sorghum planted in rows at 45 and 90 cm performs eq;ally well. IthankDrs.B.A. KrantzandR. W. Willey fortheir continuous suppon and advice during the study. 

Nitrogen response studies of intercropped sorghum with pigeonpea

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Nitrogen response studies of intercropped sorghum with pigeonpea

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