Study On Agronomic And Environmental Effects Of Combined Application Of Different Organic Manures With Chemical Fertilizer

A series of field exper iments established in 2014 were carried out to study the agronomic and environmental effects of the application of different types and rates of organic manures combined with chemical fertilizer in a winter wheat-summer maize rotation cropping system at Yucheng site, Dezhou Experimental Station of Chinese Academy of Agricultural Science, Shangdong Province, China. The organic manures were pig manure, chicken manure and cattle manure separately, and the application rates are 25% organic manure plus 75% chemical fertilizer, 50% organic manure plus 50% chemical fertilizer and 75% organic manure plus 25% chemical fertilizer respectively. The main results were as follows:1. Effects of different types of organic manure combined with chemical fertilizer on crop yields. At the standard rate of 225 kg N/ha input level, treatments which were applied with chicken or pig manure alone had the same increasing effects on both wheat yields and maize yields compared with treatment with the application of chemical fertilizer alone. The average yield of wheat or maize in treatments which were applied with chemical fertilizer, chicken or pig manure alone w as 40.83% or 33.11% higher than that in treatment with the application of cattle manure alone. Compared to treatments with the standard rate application, treatments which were applied with double N rate of pig manure, chicken manure or chemical fertilizer alone had no significant effects on crop yield, but the application of double rate of cattle manure could increase the wheat yield or maize yield signif icantly. At the standard rate N input level, all treatments which were applied with different rates of cattle manure combined with chemical fertilizer increased both wheat and maize yields, and wheat yields increased with the increasing rate of chemical fertilizer. However, there were no significant differences for maize yields among treatments which were applied with different rates of cattle manure combined with chemical fertilizer. Treatments which were applied with 25% or 50% cattle manure combined with chemical fertilizer had no significant effect on maize yield compared to the treatment which was applied with chemical fertilizer alone. All treatments which were applied with different rates of chicken manure or pig manure combined with chemical fertilizer had no signif icant difference, and all combination treatments presented the similar crop yields as the treatment with the application of chemical fertilizer alone.2. Effects of different types of organic fertilizer combined with chemical fertilizer on wheat and maize seed quality. At the standard rates of 225 kg N/ha input level, the promotion of treatments which were applied with chicken or pig manure alone is equal to that of treatment with application of chemical fertilizer alone, and distinctly superior to that of treatment with application of cattle manure alone. When N application rates were up to 450 kg/ha, the results did not show significant differences in winter wheat quality compared with standard N rates. At the standard rate of 225 kg N/ha input level, treatments which were applied with 25% organic manure plus 75% chemical fertilizer increased grain protein content and improve winter wheat quality. 15 indexes of wheat quality can be compressed into 3 components. The variance proportion of the first component is 60.22% and contained most data information(e.g. wet gluten). 18 different fertilization combinations are classified into 4 clusters:(1) no fertilizer treatment;(2) standard rates of cattle manure and doubled rates of cattle manure treatments;(3) standard rates of chicken manure treatment, standard rates of pig manure treatment, standard rates of chemical fertilizer treatment and combining manure and chemical fertilizer treatments under standard rates;(4) double rate of chemical fertilizer treatment, double rate of chicken manure treatment and double rate of pig manure treatment. Maize seed nutritional quality indexes among different treatments did not show significance because of the ―dilution effect‖ of crop yields.3. Effects of different types of organic fertilizer combined with chemical fertilizer on nitrogen use efficiency. At the standard rates of N input level, treatments which were applied with chicken or pig manure had similar nitrogen harvest index(NHI) and internal efficiency(IE)(the average of NHI and IE were 3.85kg/kg and 56.60 kg/kg respectively) as treatment with the application of chemical fertilizer alone. NHI and IE values of treatment with application of cattle manure alone were 3.73 kg/kg and 64.42 kg/kg. Compared with the standard N rates, the doubled rates of chicken manure or pig manure decreased crops’ NHI and IE significantly, while the doubled rates of cattle manure did not decrease crops’ NHI and IE. All treatments which were applied with different rates of cattle manure, chicken manure or pig manure combined with chemical fertilizer had no significant difference, and all combination treatments had similar NHI and IE as treatment with the application of chemical fertilizer alone. At the standard rates of N input level, treatments which were applied with chicken or pig manure alone had similar agronomic efficiency(AE) and recovery efficiency(RE) as treatment with the application of chemical fertilizer alone. AE average and RE average of treatments with application of chicken or pig manure were 19.86 kg/kg and 41.85% respectively, however, AE and RE of treatment applying cattle manure were merely 9.26 kg/kg and 15.55%. Compared with standard N rates, treatments which were applied with double rate of organic manure(cattle, chicken, pig manure) or chemical fertilizer decreased crops’ AE and RE by average of 39.16% and 23.19% respectively. Treatments which were applied with 25% or 50% cattle manure combined with chemical fertilizer had similar AE and RE as treatment with application of chemical fertilizer alone. All treatments which were applied with different rates of chicken manure or pig manure combined with chemical fertilizer had similar AE and RE as the treatment with the application of chemical fertilizer.4. Effects of different types of organic fertilizer combined with chemical fertilizer on soil nutrients. Applying organic manure alone or combining organic manure with chemical fertilizer can increase soil organic matter and total N content. Due to the first year’s results, total N and organic matter in the soil had no signif icance among different treatments. Because high level of P and K content in organic manure, resulted in more soil available K and P than treatments applying chemical fertilizer alone. Available P of treatments applying chicken or pig manure is 5-7 times greater than applying chemical fertilizer alone.5. Effects of different types of organic fertilizer combined with chemical fertilizer on NH3 volatilization. At the standard rates of N input level, treatment with application of chemical fertilizer alone has an annual NH3 volatilization of 39.63 kg/ha, and the annual NH3 volatilization is 37-87 times greater than treatments which were applied with organic manure alone. Among different organic manures, NH3 volatilization occurred the highest when applying pig manure, followed closely by chicken manure and occurred the lowest when applying cattle manure. Compared to treatments with the standard N rate application, applying double rate of chemical fertilizer, pig manure, chicken manure or cattle manure will increase annual NH3 volatilization signif icantly. Combining organic manure with chemical fertilizer increased NH3 volatilization; NH3 volatilization increased with the increasing rate of chemical fertilizer. At the standard rate of 225 kg N/ha input level, treatments which were applied with 25% organic manure plus 75% chemical fertilizer had similar NH3 volatilization rates as treatment with application of chemical fertilizer alone. NH3 volatilization occurred mainly during wheat season when applying organic manure. However, the treatments with application of chemical fertilizer mainly caused NH3 volatilization during maize season. N losses due to NH3 volatilization dur ing treatment with application of chemical fertilizer alone accounted for about 9% of N fertilizer rates whereas it only accounted for about 0.2% of N fertilizer rates when applying organic manure alone.6. Effects of different types of organic fertilizer combined with chemical fertilizer on N2 O emissions. At the standard rates of N input level, treatment with application of chemical fertilizer alone has a higher annual N2 O emissions(2.85kg/ha) than treatments which were applied with organic manure alone. Among different organic manures, the order of annual N2 O emissions from highest to lowest was pig manure(2.51kg/ha), chicken manure(1.91kg/ha), then cattle manure(1.85kg/ha). At the double fertilizer rate, N2 O emissions were above 1.5 times higher than treatments with standard N rate. All treatments which were applied with different rates of pig manure with chemical fertilizer and treatments which were applied with 25% and 50% cattle or chicken manure plus chemical fertilizer had similar N2 O emission values as treatment with application of chemical fertilizer alone. Treatments applying organic manure mainly caused N2 O emissions during wheat season, whereas treatments applying chemical fertilizer mainly caused N2 O emissions during maize season. N losses due to N2 O emissions during treatments applying chemical fertilizer alone accounted for about 0.4% of N fertilizer rates. Meanwhile, N losses due to N2 O emission during treatments applying organic manure alone accounted for about 0.3% of N fertilizer rates.7. Effects of different types of organic fertilizer combined with chemical fertilizer on nitrate nitrogen residue. Soil nitrate nitrogen residue mainly occurred in 0-100 cm layers of soil profiles. At the standard rates of N input level, treatment with application of chemical fertilizer alone had a nitrate-N residue of up to 210.34kg/ha, whereas the nitrate-N residue of applying organic manure was average of 109.44 kg/ha; soil nitrate-N residue among the three types of organic manure had no signif icant difference. Under doubled rates(450kg N/ha), the pig manure treatment had the most nitrate-N residue, followed by the chicken manure treatment, then the cattle manure treatment. Compared to the standard N rates, soil nitrate-N residue of doubled chemical fertilizer treatments increased about 100%; treatments which were applied with organic manure also had more soil nitrate-N residue. Among the combination treatments, treatments which were applied with 25% organic manure had a similar content of nitrate-N residue as treatment applying chemical fertilizer alone. Considering crop growth and the environment based on soil nitrate-N residue content the appropriate treatments included: treatments applying organic manure alone, treatments applying more organic manure, the double cattle manure treatment.8. Scientific application rates and types of different organic manure. In this region, under farmer’s N rates(225kg/ha), the recommended application rates of cattle manure, chicken manure and pig manure were found to be as follows:(1) chicken manure or pig manure s hould be combined with a low ratio of chemical fertilizer;(2) chicken manure or pig manure could also be applied alone in wheat season and top-dress chemical fertilizer in maize season;(3) cattle manure should be combined with a high ratio of chemical fertilizer in wheat season and chemical fertilizer rates should be reduced in maize season. Considering the high level of P and K content in organic manure, chemical fertilizer containing P and K should be applied in moderation or not at all to avoid resource waste and environmental risk.