| With the increasing prominent of the problems about agricultural non-point source pollution, more andmore attention is paid to farmland pollution prevention, and high-yield results in increasing ofagricultural nutrient inputs. Bio-active humic acid is one of the important ways to balance the crop yieldand nutrient loss from runoff and leaching. In this study, the effects of bio-active humic acid on yieldand control of nutrient loss in four different fertilizer methods including no fertilizer was observed. Andthe role of bio-active humic acid on yield and control of nutrient losing from runoff and leaching,growth of bok choy and changes of soil nutrient through laboratory tests and field trials was discussed.The main findings of the study are as follows:Indoor tests of effects of bio-active humic acid on bare land showed that after bio-active humic acid wasapplying, the soil nitrogen loss from runoff and leaching of every treatment was decreased to differentextent. The activation of bio-active humic acid to phosphorus and the stimulation of yield was observed.It was that phosphorus of no fertilizer treatment, compound fertilizer treatment and ordinary organicfertilizer treatment was attivated, but the phosphorus of bio-organic fertilizer was inhibited. Except forthe bio-organic fertilizer treatment, phosphorus leaching of other treatments was decreased withbio-active humic acid. Moreover, bio-active humic acid has control effect COD (Chemical OxygenDemand, is an important indicator of organic pollution in water) flow from runoff and leaching of alltreatments were decreased by bio-active humic acid. However, compound fertilizer treatment andordinary organic fertilizer treatment increase. Laboratory tests preliminarily indicated the effects ofbio-active humic acid on nitrogen and COD loss of different fertilizer treatments. But the effects onphosphorus need to be certified in the field trials.Field trials of effects of bio-active humic acid on bare land showed that bio-active humic acid has a verysignificant effect on the control of soil nitrogen, phosphorus and COD loss through runoff. Bio-activehumic acid reduced soil nitrogen runoff-loss rates of no fertilizer treatment, compound fertilizertreatment, ordinary organic fertilizer treatment and bio-organic fertilizer treatment by29.28%,54.54%,26.35%and49.09%. And soil phosphorus runoff-loss rates were decreased by33.97%,55.44%,32.20%and32.66%. Moreover, COD of runoff liquid were lowered about48.02%,51.51%,41.65%and35.94%. Conclusions of Laboratory tests have been verified here. Activeted phosphorus is fullyabsorbed by plants and thus total phosphorus loss amount declined than treatments without bio-activehumic acid. And addition of plant P accumulation and utilization of fertilizer P also indirectly proved this point.Bio-active humic acid also has a very significant effect on the control of soil nitrogen, phosphorus andCOD loss through leach. It reduced soil nitrogen leach-loss rate of no fertilizer treatment, compoundfertilizer treatment and bio-organic fertilizer treatment by32.34%,31.19%and33.31%. And soilphosphorus leach-loss rate are decreased by48.25%,55.72%,20.99%and4.45%. Moreover, COD ofleach liquid are lowered about40.99%,60.87%,53.09%and54.73%.Bio-active humic acid can significantly increase yield of bok choy of no fertilizer treatment, compoundfertilizer treatment and ordinary organic fertilizer treatment by70.70%,54.74%and30.76%. And theyield of bio-organic fertilizer treatment stabilizes basically. Simultaneously, nitrogen, phosphorus andsoluble sugar content of every treatment were not reduced. Moreover, no fertilizer treatment andcompound fertilizer treatment did not have significant different in vitamin C. But ordinary organicfertilizer treatment and bio-organic fertilizer treatment increased the vitamin C by20.32%and20.45%significantly.With the application of bio-active humic acid, soil total nitrogen of bio-organic fertilizer treatment wasincreased by38.36%significantly, but no fertilizer treatment reduced by28.56%. Every treatmentexcept no fertilizer treatment had a significant increase in soil nitrate with45.82%,2674.34%and30.63%. And significantly, soil ammonia nitrogen of no fertilizer treatment increased by13.66%,reduced by21.55%for ordinary organic fertilizer treatment. At the same time, alkaline hydrolyze N ofno fertilizer treatment, compound fertilizer treatment and bio-organic fertilizer treatment significantlyheighten166.67%,80.00%and162.50%. However, ordinary organic fertilizer treatment’s reduced by63.64%. Bio-active humic acid also acts on phosphorus. It significantly increased soil total phosphorusof no fertilizer treatment and bio-organic fertilizer treatment by24.84%and20.33%, but decreased thetotal phosphorus of ordinary organic fertilizer treatment by8.92%. Simultaneously, soil availablephosphorus of compound fertilizer treatment and bio-organic fertilizer treatment significantly wereincreased by98.28%and25.06%, but significantly reduced by31.69%soil available phosphorus ofordinary organic fertilizer treatment.The highest Input-output ratio treatment was no fertilizer and no bio-active humic acid treatment (CK)which had the lowest inputs, and it was1/50.64. The second and third were bio-organic fertilizerwithout bio-active humic acid treatment (BF) and bio-organic fertilizer with bio-active humic acidtreatment (BFB), they were1/6.27and1/4.97. The lowest one is ordinary organic fertilizer withoutbio-active humic acid treatment, which was only1/1.79.Considering the quality of vegetables, the two highest revenue treatments were BF and BFB. Theybrought us56617.24and54531.75Yuan. Descending order of the remainders is ordinary organicfertilizer with bio-active humic acid treatment (OFB), compound fertilizer with bio-active humic acidtreatment (CFB), compound fertilizer without bio-active humic acid treatment (CF), OF, CK and nofertilizer but applying bio-active humic acid treatment (CKB).According to the yield, quality, soil nutrients, nutrient content of runoff and leaching liquid and othertotal of16indicators, and using principal component analysis, a consolidated results rank was obtained. The descending order is stated below: BFB, BF, CFB, OFB, OF, CKB, CF, CK. It showed thattreatments with bio-active humic acid were better than ones without bio-active humic acid incomprehensive benefits. Without bio-active humic acid, the best fertilizer is bio-organic fertilizer. Whenbio-active humic acid is applied, bio-organic fertilizer with bio-active humic acid treatment has thehighest comprehensive benefits and no fertilizer and no bio-active humic acid treatment has the lowestbenefits. |
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