**6.2.2 Effect of AAF on biomass and utilization of N and P**

The plant biomass production in fresh weight was found to be significantly higher (*P* < 0.01) in the AAF treatments (mean biomass in fresh weight of A1, A2 and A3 are 5.056, 4.738 and 4.653 Kg m–2, respectively) compared with the control (mean biomass in fresh weight is 4.026 Kg m–2) (Table 18). Among AAF treatments, the treatment with low concentration of AAF (A1) had a higher (*P* > 0.05) biomass production than the treatment with high concentration of AAF (A3). The response of biomass production in dry weight to AAF treatments resembled that in fresh weight (Table 28), with significant influence by applying AAF (*P* < 0.01). The highest biomass production in dry weight was found in A1, with an increase of 17% in relation to A0.


Values are means ± SD (n=3). Analysis of variance (ANOVA) was employed followed by Duncan's new multi range test. Values with similar superscripts are not significantly different (P>0.05)

Table 18. Effect of amino acid fertilizer on radish yield and utilization of nitrogen and phosphorus 35 day after sowing (g m–2)

The result of N utilization (Table 18) was similar to biomass production as described above, again registering the highest value in A1 (14.48 ± 0.89 g m–2), with an increase of 55% compared with A0 (9.33 ± 0.87 g m–2) (*P* < 0.01). Furthermore, significant effects were observed in A2 and A3 too, with increases of 40% and 37% respectively, in relation to A0 (*P* < 0.01). Even though P content was not influenced by the application of AAF (Table 20), P utilization increased in AAF treatments due to the increase of biomass production (Table 18).

The observed result of vegetation cover and calculated values of net N uptake are showed in Table 19. The treatments of AAF showed higher vegetation cover than the control. Besides the N input by applying of AAF, the treatments of AAF showed significant increase of 36~55%net N uptake compared with the control. Gunes et al. (1996) suggested that plants probably preferred amino acids as sources of reduced nitrogen, but they did not distinguish origin of the N contents in the plants. In our experiment, the increase of N uptake is about 200 times (Table 19) more than N supplied by applying AAF, indicating application of AAF could enhance the ability of uptake and assimilation of inorganic N by plants.


Values are means ± SD (n=3). Analysis of variance (ANOVA) was employed followed by Duncan's new multi range test. Values with similar superscripts are not significantly different (P>0.05)

Table 19. Net nitrogen uptake and vegetation cover of radish

Effect of Mixed Amino Acids on Crop Growth 149

The chemical properties of soil in middle growth period and at the end of experiment were showed in Table 21 and Table 22. The planting of radish affected total N of soil clearly, except at 35 days after sowing, with a fall of 10% compared with non planting treatment. However, there were no differences in total N of soil among treatments planted with radish. On the other hand, either planting treatment or AAF treatment showed effect on nitrate in

**matter** 

NP 6.3 81 15.4 267 0.70 75.3 A0 6.3 57 15.2 297 0.67 52.5 A1 6.4 55 15.6 285 0.67 55.7 A2 6.5 65 15.1 310 0.67 58.9 A3 6.4 54 15.3 305 0.66 60.0 Table 21. Chemical properties of soil in the middle of growth period (25 day after sowing)

In the soil of non planting, nitrate was decreased by leaching and runoff by rain. Compared with the non planting treatment, the treatments of planting showed 20~30% decrease at 25 days after sowing and 23~42% decrease at 35 days after sowing in the nitrate content of soil. Although with the lowest net N uptake, the lowest concentration of nitrate in soil was found in A0 treatment both at two sampling times. This was due to the fact that the vegetation covers of AAF treatments were higher than treatment of A0, and could effectively prevent nitrate of soil from leaching or runoff. The planting treatments showed lower values of EC than non planting treatment, but all were in the range of general soil. There were no significant differences among all treatments in pH and organic matter of soil. Moreover, very small differences were observed in available P due to different growth rate of the

**matter** 

experiment 6.0 191 15.8 279 0.87 191.2 NP 6.4 99 15.9 308 0.70 94.3 A0 6.4 41 16.0 283 0.63 55.0 A1 6.4 42 15.8 263 0.63 65.9 A2 6.4 49 15.2 270 0.63 65.0 A3 6.4 45 15.3 272 0.63 73.2 Table 22. Chemical properties of soil at the end of field experiment (35 day after sowing) for

**Available P2O5** 

**(1:5) (mS m–1) (g Kg–1) (mg Kg–1) (g Kg–1) (mg Kg–1)** 

**Total** 

**<sup>N</sup>NO3––N** 

**Available P2O5**

**(1:5) (mS m–1) (g Kg–1) (mg Kg–1) (g Kg–1) (mg Kg–1)** 

**Total** 

**<sup>N</sup>NO3––N** 

**6.2.4 Effect of AAF on chemical properties of soil** 

**Treatments pH EC Organic** 

**Treatments pH EC Organic** 

soil.

for radish

plants.

Before

radish

These results are in agreement with those observed by Chen et al. (1997), who reported that application of amino acids led to positive effects on cabbage growth. However, among the treatments of AAF, the growth responses were decreased by increasing the application rate of AAF. This may probably be related to the feed–back inhibition of high rate application of amino acids.
