Research On Dynamic Changes Of Nitrogen Components In Reclaimed Soil Based On Three Organic Materials Fertilized Homesteads

Aiming at current conditions of increasing area proportion of abandoned homesteads in rural areas of China, research is made on effect from different agricultural organic fertilized materials to nutritional contents of reclaimed soil in homesteads. It can improve the recycling usage of organic materials and provide scientific theoretical basis to reclamation and utilization of homesteads in Chengdu plain. In order to research the dynamic changes of nitrogen components in soil nutrients based on organic materials fertilized homesteads, this paper selects three organic materials containing straws, bacterial residues, pig manures as test materials. Based on fixed carbon nitrogen ratios, it regards the total amount and 1.5 times of organic matter in straws as standards. It sets treatments including the blank control, pure chemical fertilizer, full amount of straws fertilized by low nitrogen chemical fertilizer,1.5 times amount of straws fertilized by high nitrogen chemical fertilizer, bacterial residues with equal carbon amount in full amount of straws fertilized by low nitrogen chemical fertilizer, bacterial residues with equal carbon amount in 1.5 tines amount of straws fertilized by high nitrogen chemical fertilizer, pig manures with equal carbon amount in full amount of straws fertilized by low nitrogen chemical fertilizer, pig manures with equal carbon amount in 1.5 tines amount of straws fertilized by high nitrogen chemical fertilizer. Using field trials and mathematical statistics, dynamic changes of nitrogen components are studied in two soil layers with thicknesses of 0-20cm and 20-40cm, which are fertilized by three organic materials. The analytical contents include total nitrogen in soil, alkali-hydrolyzable nitrogen, nitrate ritrogen, ammonium nitrogen and organic nitrogen components. The main conclusions are as follows:(1)The TN concentrations in reclaimed soil in different treatments showed significant (P<0.05) difference. The TN concentrations in reclaimed soil of homestead which is fertilized by three organic materials increase 0.10-0.30 g/kg before the reclamation, and better than the chemical fertilizer treatment. Such as nitrogen conditions, three organic materials effect to the promotion of rural homestead soil total nitrogen content show that straws>bacterial residues>pig manures, have better cumulative effects on total nitrogen in two soil layers than pig manures. The 150% field-returning amount of straws has better cumulative effect on total nitrogen in 0-20cm and 20-40cm soil layers respectively, by contrast increased 40.23%?24.23%? The promoting effect is inconsistent from unitary organic material fertilizer to total nitrogen content in soil. The results from subtractive comparison of blank control show that the unitary organic material fertilizer reaches the best promoting effect on total nitrogen content in soil under high nitrogen chemical fertilizer treatment. Straw per kilogram, which is fertilized into soil of homesteads, can improve 3.71 mg/kg of total nitrogen content in 0-20 cm soil layer. Unitary fertilized straw improves 2.91 mg/kg of total nitrogen content in 20-40 cm soil layer.(2) Alkali-hydrolyzable nitrogen in soil changes before and after the reclamation, which the contents have an overall increasing trend in comparison 4.01-28.45 mg/kg before reclamation. The AN contents are higher under field-returning treatment of three organic materials than the chemical fertilizer treatment in both 0-20cm and 20-40cm layers,.and more than 1.66%-22.88%?7.63%-15.41%? Such as nitrogen conditions, three organic materials are aligned with bacterial residue?straw>pig manure in descending order. Among them, the mushroom residue with high nitrogen fertilizer processing under the homestead soil alkali-hydrolysable nitrogen content increase the highest, increased before the reclamation 60.26%(0?20 cm) and 46.19%(20-40 cm).(3) A The changing tendencies of ammonium nitrogen are the same in growth periods of rotational in both 0-20cm and 20-40cm layers. Compared with nitrogen fertilizer only, field-returning treatment of three organic materials is beneficial to the increment of ammonium nitrogen in soil, the mushroom residue with high nitrogen fertilizer treatment of bacterial residues has the best cumulative effect on ammonium nitrogen in two soil layers among the field-returning treatment of three organic materials. The amounts of ammonium nitrogen reach 3.59 g/kg (0-20cm)?3.08g/kg(20-40 cm) at the end of planting respectively that are greatly higher than bacterial residues and pig manures (P<0.05). The amounts of nitrate nitrogen contents in two soil layers under conditional treatment of three organic materials are aligned with bacterial residues>straws>pig manures in descending order after two-year planting. The mushroom residue with high nitrogen fertilizer treatment of bacterial residues has the maximum increments in two soil layers, which has the increments of 7.72 mg/kg (0-20 cm) and 5.63 mg/kg (20-40 cm), and.it has significantly higher efficiency on organic nitrogen content in soil than straw and pig manures treatments (P<0.05)4. The organic nitrogen content is influenced by different treatments, which the contents have an overall increasing trend in comparison86.30-224.97 mg/kg before reclamation. And the organic nitrogen content in 0-20cm layers soil is higher than in 20-40cm layers soil. At the same nitrogen conditions, three organic materials are aligned with straw>bacterial residuopig manure in descending order. In terms of accumulated contents of acid-hydrolyzable nitrogen, it represents that the largest increment is 224.97 mg/kg (0-20 cm) and 180.64 mg/kg (20-40 cm) under 1.5 times amount of straws fertilized by high nitrogen chemical fertilizer treatmen. It presents to certain extent that 150% field-returning treatment of straws has significantly higher efficiency on organic nitrogen content in soil than bacterial residues and pig manures (P<0.05).