Effects of Nitrogen and Phosphorus Fertilizers and

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Effects of Nitrogen and Phosphorus Fertilizers and Intercropping on Uptake of Nitrogen and Phosphorus by Wheat, Maize, and Faba Bean Wenxue Li

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, Long Li , Jianhao Sun , Fusuo Zhang & Peter Christie

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Department of Plant Nutrition, China Agricultural University, Key Laboratory of Plant–Soil Interactions, MOE, Key Laboratory of Plant Nutrition, Ministry of Agriculture, 2 Yuan Ming Yuan West Road, Beijing, 100094, P.R. China b

Institute of Soils and Fertilizers, Gansu Academy of Agricultural Sciences, Lanzhou, P.R. China c

Department of Agricultural and Environmental Science, Queen's University Belfast, Belfast, UK d

Laboratory of Environmental Remediation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, P.R. China Version of record first published: 24 Jun 2011.

To cite this article: Wenxue Li, Long Li, Jianhao Sun, Fusuo Zhang & Peter Christie (2003): Effects of Nitrogen and Phosphorus Fertilizers and Intercropping on Uptake of Nitrogen and Phosphorus by Wheat, Maize, and Faba Bean, Journal of Plant Nutrition, 26:3, 629-642 To link to this article: http://dx.doi.org/10.1081/PLN-120017670

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JOURNAL OF PLANT NUTRITION Vol. 26, No. 3, pp. 629–642, 2003

Effects of Nitrogen and Phosphorus Fertilizers and Intercropping on Uptake of Nitrogen and Phosphorus by Wheat, Maize, and Faba Bean Wenxue Li,1,4 Long Li,1 Jianhao Sun,2 Fusuo Zhang,1,* and Peter Christie1,3 1

Department of Plant Nutrition, China Agricultural University, Key Laboratory of Plant–Soil Interactions, MOE, and Key Laboratory of Plant Nutrition, Ministry of Agriculture, Beijing, P.R. China 2 Institute of Soils and Fertilizers, Gansu Academy of Agricultural Sciences, Lanzhou, P.R. China 3 Department of Agricultural and Environmental Science, Queen’s University Belfast, Belfast, UK 4 Laboratory of Environmental Remediation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, P.R. China

ABSTRACT One-third of all the cultivated land area is used for multiple cropping and half of the total grain yield is produced with multiple cropping in China. *Correspondence: Fusuo Zhang, Department of Plant Nutrition, China Agricultural University, and Key Laboratory of Plant Nutrition, Ministry of Agriculture, 2 Yuan Ming Yuan West Road, Beijing 100094, P.R. China; E-mail: [email protected]. 629 DOI: 10.1081=PLN-120017670 Copyright # 2003 by Marcel Dekker, Inc.

0190-4167 (Print); 1532-4087 (Online) www.dekker.com



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Li et al. There have been numerous studies on nutrient acquisition by crops in legume=non-legume intercropping systems, but few on nutrient uptake in cereal=cereal intercropping. This paper describes a field experiment in which integrated wheat=maize and maize=faba bean systems were compared with sole wheat and sole faba bean cropping to assess the effects of intercropping on nutrient uptake by wheat, maize, and faba bean under various application rates of nitrogen (N) and phosphorous (P) fertilizers. Results show that both N and P fertilizers and intercropping enhanced N uptake by wheat, while only P fertilizer and intercropping increased P acquisition by wheat. The advantage of N uptake by border rows of wheat intercropped with maize declined with increasing N fertilizer application rate, but that of P acquisition was not affected by P fertilizer. The amounts of both N and P taken up by maize intercropped with faba bean were much higher than those by maize intercropped with wheat throughout the period of intercropping. Both fertilization and intercropping did not influence the N and P uptake by faba bean. Key Words: Faba bean; Intercropping; Fertilizer; Maize; Nutrient acquisition; Wheat.

INTRODUCTION Intercropping is a practice quite possibly as old as settled agriculture[1] and has been practised in China for over 2000 years. Intercropping can offer many advantages, such as more efficient use of resources, economic savings, insurance against crop failure;[2] environmental advantages by reducing the accumulation of NO3-N in the soil profile,[3] and reducing N inputs.[4] Wheat=maize and maize=faba bean intercropping systems have become widespread in north-western China, especially in Gansu province. However, most research, including that on nutrient acquisition,[5–8] has concentrated on legume=non-legume systems, with few reported studies on cereal=cereal intercropping. Li[9] and Li et al.[10] published data from two studies on intercropping at one field site and reported the following results. Firstly, intercropping enhanced nutrient acquisition by the crops. Secondly, both border-row and inner-row effects contributed to increased nutrient acquisition by intercropped wheat. Thirdly, border-row effects in intercropping systems could be attributed to differences in competitive ability for nutrients between wheat and maize or soybean and faba bean. However, their studies were mainly concerned with agronomic practice and P fertilizer utilization. In contrast, the objective of this field study was to examine the impact of intercropping on nutrient uptake by


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wheat, maize, and faba bean under different application rates of both N and P fertilizers.

MATERIALS AND METHODS Study Area The field experiment was carried out in 2000 at the Baiyun experimental site of the Institute of Soils and Fertilizers, Gansu Academy of Agricultural Sciences. The site (38 370N, 102 400E) is located 15 km north of Wuwei City, Gansu Province, at an altitude of 1504 m asl. Annual mean temperature is 7.7 C and average cumulative temperatures above 0 C and 10 C are 3646 C and 3149 C, respectively. The frost-free period is 170–180 days and total solar radiation is 5988 MJ m2 year1. Mean annual precipitation is 150 mm and potential evaporation is 2021 mm. The site has been described in some detail in a previous paper.[10] The soil in the experiment contained 19.1 g organic matter, 1.18 g total N, 17.3 mg Olsen-P, and 233 mg exchangeable K kg1 dry soil.

Wheat=Maize=Faba Bean Intercropping The experiment was a split–split-plot design with main treatments being fertilizer N applications (as NH4NO3) of at the rates of 0, 100, 200, 300 and 400 kg N ha1. The sub-main-plot treatments consisted of 0 and 33 kg P ha1, applied as triple superphosphate. Sub-plot treatments were composed of sole spring wheat (Triticum aestivum L. cv. 8354), sole faba bean (Vicia faba L. cv. Linxia Dadou), maize (Zea mays L. cv. Zhongdan No. 2)=wheat intercrop, and maize=faba bean intercrop. There were three replicate plots of each treatment in a random block. The wheat=maize planting pattern consisted of five rows of wheat and two rows of maize. The maize=faba bean intercrop comprised two rows of maize and three rows of faba bean. Sole wheat and sole faba bean were made up of 16 and eight rows respectively. The row spacing of wheat, maize, and faba bean was 0.12, 0.4, and 0.2 m, respectively. The densities of sole wheat and faba bean were 675 and 12.5 plants=m2. The intercropped area of wheat and faba bean occupied three-sevenths of wheat=maize and three-fifths of maize=faba bean respectively, and the densities of intercropped wheat and faba bean were therefore 288 and 7.5 plants=m2. Accordingly, the densities of maize intercropped with wheat and with faba bean were 7 and 5 plants=m2.



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Seeds of wheat and faba bean were sown on March 20 and of maize on April 9. Dates of harvesting were July 15, August 1, and September 25 for wheat, faba bean and maize, respectively. All of the P fertilizer and 100 kg N ha1 (except for the N0 treatment which received no N fertilizer) were uniformly broadcast and ploughed into the soil before sowing. The remainder of the N fertilizer applications was made by topdressing at the shooting stage of wheat and the pre-tasselling stage of maize. All plots were irrigated with 75 mm of water six times during the growing season to prevent water stress. All of the plants in the plots were harvested at maturity and the yields were recorded. Plant samples were air-dried at 60 C and milled. Subsamples were digested with H2SO4–H2O2, and N was determined by the microKjeldahl procedure and P by the vanadomolybdate method. Nutrient uptake was calculated by multiplying the nutrient concentrations in the aboveground parts by the aboveground yields of the crops. Statistical Analysis The treatments were compared using analysis of variance (ANOVA) and mean uptake of N and P by different rows of wheat intercropped with maize was compared using least significant difference (LSD) at the 5% level.[11] RESULTS Wheat Nutrient Acquisition There was a general increasing but not significant (compared with control) trend in N uptake by wheat with increasing application rate of fertilizer N averaged over both P levels and both cropping regimes (P < 0.05). The uptake rates were 143 and 145 kg N ha1 at 400 and 300 kg applied N ha1 respectively (Table 1). The main factor affecting N uptake was cropping regime, with significantly higher N uptake by wheat in the intercropping system compared with monoculture (P < 0.01). Application of P fertilizer at the rate of 33 kg ha1 had no significant effect on N uptake (Table 1). Neither fertilizer P application nor application rate of N fertilizer had any effects on wheat P uptake (Table 1). As in the case of N uptake, P uptake by wheat intercropped with maize was significantly greater than that of wheat in monoculture (P < 0.01).


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Table 1. Effects of N and P fertilizer application rates on N and P uptake by wheat in monoculture and intercropped with maize. 33 kg P fertilizer ha1 applied


No P fertilizer applied N fertilizer rate (kg ha1) N acquisition kg ha1 0 100 200 300 400

Sole wheat

Intercroppeda

Sole wheat

Intercroppeda

78.6 87.8 114.7 94.9 101.4

158.5 151.5 173.1 174.0 174.9

100.6 106.9 102.6 139.0 126.5

144.1 181.1 162.6 172.5 169.6

21.0 19.9 17.1 19.8 21.9

26.9 26.4 22.6 27.8 25.0

Significanceb due to: N fertilizer rate P fertilizer Cropping system P acquisition kg ha1 0 100 200 300 400 Significanceb due to: N fertilizer rate P fertilizer Cropping system

* NS ** 19.3 15.9 20.6 14.7 15.8

26.4 23.5 26.0 23.5 24.4 NS NS **

a

Values are yields of intercropped crops on equivalent basis. By ANOVA. *P < 0.05. **P < 0.01. NS: Not significant. b

Border-Row Effects on Nutrient Acquisition by Wheat Because P fertilizer had no detectable effects on N acquisition by wheat, the amounts of N taken up by wheat were averaged over the two P levels. The advantage in N acquisition by border rows of wheat declined with increasing application rate of N fertilizer (Fig. 1). When no N fertilizer or 100 kg N ha1 was applied, N acquisition by wheat in border rows (rows 1, and 5) in



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Figure 1. Nitrogen acquisition by sole wheat and by wheat located in each of the five different row positions when intercropped with maize. Within each N application rate, bars with the same letter are not significantly different by LSD at the 5% level.

intercropping was significantly higher than that by the inner rows (rows 2, 3, and 4). At the higher fertilizer N application rates of 200–400 kg ha1, however, the differences in N uptake between border rows and inner rows were much less pronounced. This indicates a decrease in advantage by the border rows with increasing of N application rates. When no fertilizer N was applied and there was a marked advantage in N acquisition by border rows, the overall increase in N acquisition by intercropped wheat (averaged over all six rows) was 37% higher than that in sole cropping, and about 84% of this effect was attributable to the border rows. In contrast, when 300 kg N ha1 was applied the overall N acquisition by



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intercropped wheat was 34% higher than that by sole wheat, but only 55% of this increase was derived from the border row effect. Uptake of P was also examined by averaging the data over all N application rates because N application rate had no effect on P uptake (Table 1). The advantage in P acquisition by border rows occurred at both P levels studied (Fig. 2). When no P fertilizer was applied, P acquisition by the border rows of wheat was 0.34 g m1 row1, much greater than that of the inner rows and in sole cropping. The P uptake by the inner rows was also greater than that in sole wheat. When 33 kg fertilizer P ha1 was applied, P uptake by the sole wheat was slightly higher than in the unfertilized treatment and was not significantly different from that of the inner rows of intercropped wheat.

Maize Nitrogen acquisition by maize was significantly affected by the application rate of N fertilizer (Table 2). At the pre-tasselling stage N uptake increased with increasing rate of N fertilizer in both intercropping systems. The difference between the plants receiveing no N fertilizer and those receiving N fertilizer was much more pronounced in the maize=faba bean system at the pre-tasselling stage. Nitrogen acquisition by maize in the wheat=maize system was much lower than in maize=faba bean system. Differences between plants receiving no N fertilizer and those receiving N fertilizer in the wheat=maize system still existed but were less pronounced at maturity. In the maize=faba bean system, N acquisition increased at the lower rates of fertilizer N and decreased at higher N rates compared with the pre-tasselling stage.

Figure 2. Phosphorus acquisition by sole wheat and by wheat located in each of the five different row positions when intercropped with maize. Within each P level, bars with the same letter are not significantly different by LSD at the 5% level.


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Table 2. Effects of N and P fertilizer application rates on N uptake by maize (kg ha1) intercropped with wheat or faba bean at the pre-tasselling stage and at maturity.


Maize intercroppeda with wheat

Maize intercroppeda with faba bean

N fertilizer rate (kg ha1)

No P fertilizer

33 kg P ha1

No P fertilizer

33 kg P ha1

Pre-tasselling 0 100 200 300 400

42.7 87.6 179.8 246.7 232.0

37.8 132.6 170.7 150.9 256.0

153.3 160.9 238.3 268.1 307.3

99.7 165.4 196.4 248.5 367.3

Significanceb due to: N fertilizer P fertilizer Cropping system At maturity 0 100 200 300 400 Significanceb due to: N fertilizer P fertilizer Cropping system

** NS

** NS **

108.1 150.5 208.0 224.6 269.4

128.5 209.6 210.7 244.5 232.8

175.6 244.2 278.0 216.2 242.9

** NS

166.0 187.4 292.7 260.2 298.8 * NS

**

a


In the absence of fertilizer P, N acquisition by maize in the maize=faba bean system at zero-N and low N fertilizer rates was still higher than in the maize=wheat system but the opposite trend occurred at the two highest fertilizer N rates. When 33 kg P ha1 was applied N acquisition by maize in the maize=faba bean system was consistently much higher than in the maize=wheat system even at the highest application rates of N fertilizer.



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Phosphorus acquisition by maize at the pre-tasselling stage was significantly enhanced by N fertilizer application and had no relationship with P fertilizer application (Table 3). In the wheat=maize system, P acquisition by maize receiving N fertilizer was much higher than that receiving no fertilizer N and there was little difference between fertilizer N rates. The pattern of results was similar in the maize in maize=faba bean system, but the maize receiving no fertilizer N took up much more N than in the maize=wheat system.

Table 3. Effects of N and P fertilizer application rate on P uptake by maize (kg ha1) intercropped with wheat or faba bean at the pre-tasselling stage and at maturity. Maize intercroppeda with wheat

Maize intercroppeda with faba bean

N fertilizer rate (kg ha1)

No P fertilizer

33 kg P ha1

No P fertilizer

33 kg P ha1

Pre-tasselling 0 100 200 300 400

8.0 16.7 20.8 24.8 29.6

7.8 17.7 21.6 18.3 30.2

21.0 19.4 27.9 29.1 35.5

16.1 20.1 26.6 28.7 44.9

Significanceb due to: N fertilizer P fertilizer Cropping system At maturity 0 100 200 300 400 Significanceb due to: N fertilizer P fertilizer Cropping system a

** NS

* NS **

31.7 49.8 60.6 59.7 58.8

40.8 65.8 57.5 72.6 65.9

59.2 72.4 83.9 60.7 60.1

* *

NS NS **


54.1 62.7 75.4 75.2 76.7



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At maturity both N and P fertilizers increased P acquisition by maize in wheat=maize intercropping. The changes in wheat=maize intercropping under different rates of N fertilizer were very similar to the pre-tasselling stage, but P acquisition in the P-fertilized treatments amounted to 60.5 kg ha1, which was higher than that in treatments receiving no fertilizer P. In maize=faba bean intercropping, only N fertilizer significantly affected P acquisition by maize. Overall, P acquisition by maize in maize=faba bean intercropping was significantly higher than in the wheat=maize system regardless of growth stage, especially in the crops receiving no N fertilizer.

Faba Bean Nitrogen and P uptake by sole faba bean and faba bean intercropped with maize are shown in Table 4. Neither fertilizer N nor fertilizer P had any influence on N or P uptake by faba bean. Intercropping also had no detectable effect on N or P acquisition by faba bean.

DISCUSSION In the wheat=maize system, intercropped wheat acquired much more N and P than did sole wheat. This may be due to a difference in competitive ability for N and P uptake between wheat and maize during their period of co-existence. Li et al.[10] showed that the aggressiveness of wheat relative to maize was 0.26–1.63 and this indicated the greater potential capacity of wheat than maize to take up nutrients in intercropping systems compared with sole cropping. In the present study N acquisition advantage by border rows of wheat clearly occurred when no fertilizer N was applied or when only 100 kg of fertilizer N ha1 was applied and the effect declined with increasing application rate of N fertilizer. A yield advantage of wheat growing in border rows has been frequently observed.[10,12] This yield advantage may be the major basis for N uptake advantage by border rows because there were no observed differences in straw or grain N concentrations between inner rows and border rows (data not shown). Boundary effects of wheat may be attributed to several factors. The main factor under high fertility conditions was found by Chen et al.[13] to be light, while water and fertilizer supplies were the main factors under low fertility conditions. This could explain the N acquisition results in the present experiment. Under low N conditions, the border rows may have competed for N not only with maize but also with the inner rows of wheat.


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Table 4. Effects of N and P fertilizer application rate on N and P uptake by faba bean (kg ha1) in monoculture and intercropped with maize. 33 kg P fertilizer ha1 applied


No P fertilizer applied cN fertilizer rate (kg ha1)

Sole faba bean

Intercroppeda

Sole faba bean

Intercroppeda

N acquisition 0 100 200 300 400

365.4 238.9 300.0 185.3 321.8

347.7 265.7 255.0 217.8 300.3

455.6 271.5 299.5 289.5 427.0

316.9 281.9 234.6 249.4 304.9

59.9 39.8 46.1 43.4 53.0

39.9 36.9 32.7 34.4 42.0

Significanceb due to: N fertilizer rate P fertilizer Cropping system P acquisition 0 100 200 300 400 Significanceb due to: N fertilizer rate P fertilizer Cropping system

NS NS NS 46.9 33.8 42.1 22.9 42.7

46.8 37.5 33.8 29.6 38.3 NS NS NS

a

Values are yields of intercropped crops on equivalent basis. By ANOVA. NS: Not significant. b

As the N fertilizer application rate increased, the available N may have met the requirements of both border and inner rows of wheat, resulting in the observed decline in N acquisition advantage of the border rows at the higher N application rate. The re-appearance of boundary effects under the highest N application rate may have been due to P which had become a limiting yield factor for the wheat. In the case of P acquisition, boundary effects always occurred and this may have been due, at least in part, to the relative immobility of P in the soil.



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Nitrogen acquisition by maize intercropped with faba bean was much higher than that of maize intercropped with wheat at both growth stages investigated. This may be attributable to both direct and indirect transfer of fixed N to the intercropped non-legume.[14,15] This N transfer may have occurred through root excretion, N leached from leaves or leaf fall.[16] Published evidence suggests that N2 fixed by a legume component might be available to the associated cereal in the current growing season,[17] but there have been numerous reports of little or no current N transfer occurring in legume=cereal intercropping.[18] In studies on bean=maize intercropping,[15] although different methods indicated that maize had derived N from associated bean, no benefit could be observed in increased N uptake by the maize. Thus the increase in N acquisition by maize intercropped with faba bean in the present study may have not been due solely to biological N fixation, in soil condition or amelioration of pest infestation. The much lower N acquisition by maize at maturity under high N application rates than at the pre-tasselling stage may have been due to senescence leading to leaf fall. Phosphorus acquisition by maize intercropped with faba bean was significantly higher than that of maize intercropped with wheat. This may have arisen from biological N2 fixation by faba bean and characteristics of root distribution. Legumes release more Hþ into the soil when fixing N2.[19] The resulting acidification of the rhizosphere may enhance the mobilization of insoluble P in the soil. In the wheat=maize system wheat roots have been observed to proliferate under the maize root systems, but few roots of maize spread under the wheat roots before the wheat is harvested. In contrast, in the maize=faba bean system the roots of maize spread under the faba bean even before the faba bean is harvested.[9] The maize plants in maize=faba bean intercropping can thus gain access to more soil P in the rows of maize in the intercrop with the legume.

CONCLUSIONS Nitrogen uptake by wheat was significantly enhanced by both intercropping and N fertilization. However, P uptake by wheat was increased only by intercropping. There were border row advantages in nutrient uptake by wheat. The effect of N declined with increasing application rate of N fertilizer. An inner row effect on P uptake by intercropped wheat occurred in which there was increased P uptake in inner rows in intercropping compared with sole cropping when no P fertilizer was applied. Nitrogen uptake by maize increased significantly with increasing rate of N fertilizer application at both the pre-tasselling stage and at maturity. Nitrogen uptake by intercropped



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maize was significantly greater when faba bean was the associated crop than when wheat was the companion crop. Phosphorus uptake by maize was increased by associated faba bean compared to wheat. Furthermore, P uptake by maize intercropped with faba bean was not affected by N and P fertilizer application, but was dependent on N and P fertilization when maize was intercropped with wheat. Uptake of N and P by intercropped faba bean was not affected by intercropping or N and P fertilizer application. The results highlight the importance of the N and P contributed by faba bean to intercropped maize in the faba bean=maize intercropping system.

ACKNOWLEDGMENTS We thank the Major State Basic Research Development Program of the People’s Republic of China (Project number G1999011707) and the National Natural Science Foundation of China (Project number 30070450) for generous financial support.

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8. Gardner, W.K.; Boundy, K.A. The acquisition of phosphorus by Lupinus albus L. IV. The effect of interplanting wheat and white lupin on the growth and mineral composition of the two species. Plant Soil 1983, 70, 391–402. 9. Li, L. Interspecific facilitative and competitive interactions between intercropped species; China Agricultural University, Beijing, 1999; Ph. D. Dissertation (In Chinese). 10. Li, L.; Sun, J.H.; Zhang, F.S.; Li, X.L.; Yang, S.C.; Rengel, Z. Wheat=maize or wheat=soybean strip intercropping. I. Yield advantage and interspecific interactions on nutrients. Field Crops Res. 2001, 71, 123–137. 11. SAS. SAS User’s Guide: Statistics, Version 5.0; SAS Institute: Cary, NC. 1985. 12. Lesoing, G.W.; Francis, C.A. Strip intercropping effects on yield and yield components of corn, grain sorghum, and soybean. Agron. J. 1999, 91, 807–813. 13. Chen, Y.H.; Yu S.L.; Yu, Z.W. Studies on the edge effect in wheat. J. Shandong Agric. Univ. 1999, 30, 431–435. 14. Van Kessel, C.; Singleton, P.W.; Hoben, H.J. Enhanced N-transfer from soybean to maize by vesicular-arbuscular mycorrhizal (VAM) fungi. Plant Physiol. 1985, 79, 562–563. 15. Giller, K.E.; Ormesher, J.; Awah, F.M. Nitrogen transfer from Phaseolus bean to intercropped maize measured using 15N-enrichment and 15 N-isotope dilution methods. Soil Biol. Biochem. 1991, 23, 339–346. 16. Fujita, K.; Ofosu-Budu, K.G.; Significance of legumes in intercropping systems. In Roots and Nitrogen in Cropping Systems of the Semi-Arid Tropics; Ito, O., Eds.; Japan International Research Center for Agricultural Sciences (JIRCAS), 1996; 20–40. 17. Ta, T.C.; Faris, M.A.; Macdowall, F.D.H. Evaluation of 15N methods to measure nitrogen transfer from alfalfa to companion timothy. Plant Soil 1989, 114, 243–247. 18. Danso, S.K.A.; Palmason, F.; Hardarson, G.; Is nitrogen transferred between field crops? Examining the question through a sweet-blue lupin (Lupinus angustifolius L.)—oats (Avena sativa) intercrop. Soil Biol. Biochem. 1993, 25, 1135–1137. 19. Tang, C.; Mclay, C.D.A.; Barton, L. A comparison of proton excretion of twelve pasture legumes grown in nutrient solution. Aus. J. Exp. Agric. 1997, 37, 563–570.