| The salt content of coastal saline-alkali soil is high, with unreasonable application of fertilizer, the degree of salinity in arable land aggravated which will not only seriously affect the yield and quality of crops, but also give great burden to the ecological environment of farmland, atmosphere, water et al. Li z-s, Chinese academy of sciences academician, put forward the program of "Bohai granary" in 2012, calling for taking advantage of local resources, advanced science and technology to build the moderate scale management of modern agricultural production technology system and boost the production ability of middle-and-low-yielding fields in Circum-Bohai Sea Region. The Yellow River delta typical coastal salinized fluvo-aquic soil was chosen as the research object in this experiment. After investing the local cultivation mode, irrigation system and fertilization management mode, field experiment and indoor analysis test have been combined to study the effects of different fertilization model of conventional fertilization, constant organic fertilizer + chemical fertilizer(1/2 basic fertilizer+1/2 additional fertilizer), incremental organic fertilizer + chemical fertilizer(1/2 basic fertilizer+1/2 additional fertilizer) to the soil nutrient, salt, and the production of wheat. Additionally, the effects of different fertilization model of conventional fertilizer(2/3 basic fertilizer + 1/3 additional fertilizer), constant organic fertilizer + chemical fertilizer(2/3 basic fertilizer + 1/3 additional fertilizer), incremental organic fertilizer + chemical fertilizer(2/3 basic fertilizer + 1/3 additional fertilizer), constant organic fertilizer + chemical fertilizer(1/2 basic fertilizer + 1/2 additional fertilizer), incremental organic fertilizer + chemical fertilizer(1/2 basic fertilizer + 1/2 additional fertilizer) to the soil nutrient, salt, and the production of cotton also been studied. The main results are as follows:In the winter wheat experiment cultivated in the moderate salinized land, compared with the conventional fertilization model(MCF,N-P2O5-K2 O, 274.2-345-0 kg/hm2, 2/3 basic fertilizer+1/3 additional fertilizer), the constant organic fertilizer(3600 kg/hm2 commercial organic fertilizer) + chemical fertilizer(N-P2O5-K2 O,278.4-98.55-180 kg/hm2,1/2 basic fertilizer +1/2 additional fertilizer)model(MNMFT) significantly reduced the water-soluble salt contents before the winter wheat irrigation(decreased by 16.5% at returning green stage, and decreased by 9.8% averagely), reduced the loss of the soil available nutrients, and increased the amounts of available N and K, showing that available N and available K respectively increased by 2.2% and 9.9% at returning green stage, increased by 3.4% and 15.2% at seed filling stage, and averagely increased by 3.8% and 15.7% at the whole growth period. With a decrease in the application rate of P fertilizer, soil available P amount could still be up to 22.48 mg/kg and wheat yields increased by 29.03%. Compared with MCF, the high organic fertilizer(7200 kg/hm2) + low chemical fertilizer(N-P2O5-K2 O, 185.6-65.7-120 kg/hm2, 1/2 basic fertilizer +1/2 additional fertilizer) model(MHMFT) not only could significantly reduce the amounts of water soluble salt(decreased by 18.3% at returning green stage, and decreased by 12.6% averagely), but also could maintain the amounts of soil available nutrient and winter wheat yields. The application of organic fertilizer significantly decreased soil bulk density(averagely decreased by 1.8% for all organic fertilizer treatments), increased SOM content(increased by 5.8%), reduced the loss of available P and K, improved soil structure and the composition of CEC, and reduced soil salt contents.In the cotton experiment cultivated in the heavy salinized land, increasing the ratio of additional fertilizer could improve the content of available nutrients at the cotton boll opening stage. Compared with HNMFB, the contents of available N, available P and available K under HNMFT treatment which applied the normal amount of organic and chemical fertilizer with a higher additional fertilizer ratio were 5.40%, 7.26% and 6.56% higher. Compared with HHMFB, HHMFT treatment with a higher additional fertilizer ratio increased the contents of available N, P, K by 7.24%, 7.30% and 18.15% respectively. The combined application of organic fertilizer and chemical fertilizer could increase the contents of soil available P, available K and SOM. At the boll opening stage, compared with HCF, HNMFB increased the contents of soil available P, available K and SOM by 9.64%, 1.94% and 16.82% respectively; HHMFB increased these indicators by 16.30%, 6.58% and 23.78% respectively; HNMFT increased those by 17.59%, 18.27% and 15.83% while HHMFT increased those by 24.46%, 13.62% and 22.57%, respectively. Increasing the application rate of organic fertilizer could reduce soil salt contents. Compared with HCF model, HHMFB and HHMFT treatments decreased the salt contents by 23.44% and 33.30% at the flowering stage, and decreased that by 17.30% and 28.84% at the boll opening stage; while HNMFB and HNMFT treatments decreased the salt contents by 12.45% and 17.03% at the flowering stage, and decreased that by 6.07% and 9.10% at the boll opening stage. The salt-reducing effect was much better in higher organic fertilizer treatments, showing that the salt content under high organic fertilizer treatments was averagely 8.84% lower than that under normal organic fertilizer treatments.In the cotton experiment cultivated under the heavy salinized land, optimized fertilization have positive effect on plant height, stem diameter, bud number, boll branch number compared with conventional fertilization, and consequently increased cotton yield. Compared with HCF, HNMFT increased plant height by 15.42%, increased stem thickness by 8.45%, increased bud number by 55.76%, flower number by 10.62% and biomass by 50.70%. Compared with the conventional treatment(HCF), HNMFB and HNMFT significantly increased(P < 0.05) the cotton yield by 20.44% and 28.68% respectively. Increasing the ratio of additional fertilizer could also increase cotton yield, showing that compared with HNMFB and HHMFB, HNMFT and HHMFT treatments increased cotton yield by 6.84% and 4.56% correspondingly.Organic fertilizer could significantly increase the proportion of soil macro-aggregate in the strongly salinized land. Proportions of > 5mm and > 0.25 mm soil aggregates were much higher in the four organic fertilizer treatments than that in the conventional fertilizer treatments. Compared with HCK, proportions of > 5mm and > 0.25 mm mechanical stable aggregate were 51.23% and 3.57% higher in HNMFB treatment, 52.63% and 13.30% higher in HHMFB treatment, 51.14% and 3.35% higher in HNMFT treatment, 52.55% and 13.73% higher HHMFT treatment, respectively. Proportions of > 5mm and > 0.25 mm water-stale aggregates of HHMFB and HHMFT were significantly higher than other treatments. Compared with HCF, these two treatments averagely increased the proportion of > 5mm water-stale aggregates by 57.8% and averagely increased the proportion of > 0.25 mm water-stale aggregates by 11.97%. Organic fertilizer could increase the MWD of the soil aggregates in Binhai strongly salinized land. Compared with the check treatment, HNMFB, HHMFB, HNMFT and HHMFT increased MWD by 30.20%, 54.36%, 36.54% and 56.57%, respectively. |
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