Effects of long-term fertilization patterns on bacterial community structure and soil nutrients in dryland of yellow soil.

Understanding the responses of soil bacterial community to long-term fertilization in dryland of yellow soil could provide theoretical basis for establishing scientific fertilization system and cultivating healthy soil. Based on a 25-year long-term fertilization experiment on yellow soil, we collected soil samples from 0-20 cm layer under different fertilization treatments: no fertilization (CK), balanced application of N, P and K fertilizers (NPK), single application of organic fertilizer (M), combined application of constant organic and inorganic fertilizer (MNPK), and 1/2 organic fertilizer instead of 1/2 chemical fertilizer (MNP). Illumina MiSeq high-throughput sequencing technology was used to examine the effects of different fertilization patterns on soil bacterial community structure and soil nutrient content. The main driving factors of soil bacterial community were explored. The results showed that soil pH and organic matter content under treatments with organic fertilizer increased by 11.4%-13.5% and 28.8%-52.0%, respectively, compared to that under NPK treatment. Long-term fertilization did not affect soil bacterial α diversity, but significantly affected soil bacterial ß diversity. Compared with CK and NPK treatment, treatments of M, MNP, and MNPK significantly changed soil bacterial community structure, and increased the relative abundance of Fusobacteria and Anaerobes. Four fertilization treatments increased the relative abundance of Bacteroidetes, and decreased the relative abundance of Actinomyces and Campylobacter, compared to CK. Soil pH was the most important factor affecting soil bacterial community structure. Fertilization-stimulated rare microbial taxa (Pumilomyces and Anaerobes) were more sensitive to changes in different environmental factors and were the main drivers of the formation of community versatility. In conclusion, organic fertilizer improved soil properties and fertility and changed soil bacterial community structure, which are conducive to cultivating healthy soil.

[Responses of soil microbial biomass C and P to different long-term fertilization treatments in the yellow paddy soil]. / 黄壤稻田土壤微生物生物量碳磷对长期不同施肥的响应.

To explore the rational fertilization mode to improve the availability of soil phosphorus (P), we analyzed the changes and coupling characteristics of soil carbon (C) and P, microbial biomass C (MBC) and P (MBP) under different fertilization modes with a successive 22-year field experiment in yellow paddy soil. The experiment had 10 treatments, including no fertilization (CK), single application of nitrogen (N), combination of phosphorus and potassium (PK), combination of nitrogen and potassium (NK), combination of nitrogen and phosphorus (NP), combination of nitrogen, phosphorus and potassium (NPK), single application of organic fertilizer (M), and three organic-inorganic fertilizer combinations (1/4M+3/4NP, 0.5MNP, MNPK). The results showed that, compared with CK, the contents of total organic C (TOC), total P (TP), MBC and MBP in N and NK treatments decreased to some extent, while those in PK, NP and NPK treatments increased. Compared with the treatments of no fertilizer and inorganic fertilizer, the contents of TOC, MBC, MBP and MBP/TP ratio in treatments with manure significantly increased, among which M and MPNK treatments showed the strongest enhancement. The treatments with manure had the lowest MBC/MBP ratio, TOC/MBP ratio and MBC/TP ratio, while N treatment had the highest value. MBC, MBP, MBP/TP ratio, MBC/MBP ratio, TOC/MBP ratio and MBC/TP ratio were significantly correlated with TOC and available P, TOC was the direct factor affecting MBC, MBP, and MBP/TP ratio, while available P was the direct factor affecting MBC/MBP ratio, TOC/MBP ratio, MBC/TP ratio. In summary, soil MBP content and the coupling relationship between C and P could effectively distinguish the modes of production with single chemical fertilizer application and manure application, and could be used as biological indices in the evaluation of soil P fertility. Combined application of manure is an effective way to enhance P availability and increase its potential capacity and maintain soil biological health in yellow paddy soil.

Occurrence characteristics of Echinochloa and its response to long-term fertilization in paddy fields of yellow soil.

We studied the characteristics of Echinochloa and its response to variation of rice yield and soil properties under long-term fertilization in paddy field of yellow soil, based on a 23-year long-term fertilization experiment in Scientific Oberving and Experimental Station of Arable Land Conservation and Agricultural Environment (Guizhou), Ministry of Agriculture. The occurrence characteristics of Echinochloa (density, panicle number per plant, totle panicles, seed number per panicle, 1000-seed mass and seed mass per panicle) of ten treatments including CK, N, PK, NK, NP, NPK, 1/4MNP, 1/2MNP, M (manure), MNPK were examined. The results showed that the characteristics of Echinochloa significantly varied with long-term different fertilization. The highest density, panicle number per plant and total panicles of Echinochloa were attained in the MNPK treatment, followed by the 1/4MNP treatment. Compared with the NPK treatment, the density of Echinochloa was significantly decreased in no fertilizer treatment (CK) and unbalanced chemical fertilizer treatments (N, PK, NK, NP). The panicle number per plant significantly increased in organic fertilizer treatments (1/4MNP, 1/2MNP, M, MNPK). Both the density and total panicles of Echinochloa were positively correlated with rice yield. The occurrence characteristics of Echinochloa were positively correlated with soil organic matter, total N, total P, available N, available P and available K. Results from path analysis showed that soil total N had a direct positive effect on panicle number per plant and soil total P content was the main factor affecting the density and total panicles of Echinochloa. Soil available K content was the factor with strongest influence on seed number per panicle and seed mass per panicle. We concluded that the occurrence characteristics of Echinochloa varied with long-term different fertilization. The density, panicle number per plant and total panicles of Echinochloa could be increased with appling cow manure. Soil total P was the direct influencing factor for the variation of density and total panicle of Echinochloa in paddy field of yellow soil.

[Effect of long-term application of NPK fertilizer on maize yield and yellow soil nutrients sustainability in Guizhou, China]. / é•¿æœŸæ°®ç£·é’¾è‚¥é æ–½å¯¹è´µå·žé»„å£¤çŽ‰ç±³äº§é‡å’ŒåœŸå£¤å »åˆ†å¯æŒç»­æ€§çš„å½±å“.

A long-term fertilization field experiment was conducted to investigate the effect of nitrogen (N), phosphorus (P), and potassium (K) fertilizer on maize relative yield, yield-increasing effect and the changes of nutrients in yellow soil in Guizhou Province. Five fertilizer combinations were evaluated, including balanced fertilization (NPK) and nutrient deficiency treatments (N, NK, NP, and PK). The maize relative yield, contribution efficiency of N, P, K fertilizer application, sustainability index of soil N, P, K nutrients, and other indicators were measured. The results revealed that the balanced fertilization (NPK) significantly increased maize yield, and the average yield under each treatment ranked as: NPK>NP>NK>PK>CK. The contribution efficiency and agronomic efficiency of N, P, K fertilizer application was N>P>K. The fertilization dependence was ranked as: combined application of N, P and K>N>P>K. But in the lack of P treatment (NK), the maize relative yield significantly decreased at a speed of 1.4% per year, with the contribution efficiency and fertilization dependence of applied P significantly increasing at a speed of 2.3% per year and 1.4% per year, respectively. Over time, the effect of P fertilizer on maize yield gradually became equal to that of N fertilizer. The pH and soil organic matter content were the lowest in the P-lack treatment (NK), while they were higher in the N-lack treatment (PK). The application of chemical P significantly improved the sustainability index of soil P, but the application of chemical N and K did not significantly change the sustainability index of soil N and K nutrients compared to the N- and K-lack treatments, respectively. In summary, the use of balanced fertilizer application is critical for achieving high maize yield in typical yellow soil regions in Guizhou Province. P and N fertilizers are equally important for improving maize yield, and long-term application of unbalanced chemical fertilizer, especially the lack of P, would not benefit the sustainable use of nutrients in yellow soil.

[Response of Olsen-P to P balance in yellow soil upland of southwestern China under long-term fertilization.] / 长期施肥条件下西南黄壤旱地有效磷对磷盈亏的响应.

Based on a long-term fertilization experiment in Guizhou Province, we explored the relationships between the soil available phosphorus (Olsen-P), soil apparent P balance and P application rate in order to quantify the best application rate of P fertilizer in yellow upland soil of southwestern China. Moreover, the response curve of crop yield to soil Olsen-P was fitted by Mitscherlich equation to determine the critical content of Olsen-P for crop yield. The results showed that the long-term application of P fertilizer could significantly increase the content of soil Olsen-P, and the increasing rates of Olsen-P across different treatments could be mainly explained by the application rate of P fertilizer. Under no-P treatment, the soil P content was in a deficient state for each year, while it displayed a surplus state in the treatments with P fertilizer, and the crop P uptake and P accumulation were found the highest under MNPK treatment. In contrast to single application of chemical fertilizer treatment (NPK), the combined application of organic fertilizer and chemical fertilizer (1/4 M+3/4 NPK, 1/2 M+1/2 NPK) could enhance crop P uptake and improve accumulative P use efficiency. The soil apparent P balance was significantly (P<0.05) correlated with soil Olsen-P. With average P accumulation of 100 kg·hm-2, the soil Olsen-P increased by 16.4, 13.0 , 21.4 , and 5.6 mg·kg-1 in the treatments of MNPK, 1/4 M+3/4 NPK, 1/2 M+1/2 NPK, and NPK, respectively. The result showed that combined application of organic fertilizer and chemical fertilizer could effectively increase the soil Olsen-P content, and the critical value of soil Olsen-P was 22.4 mg·kg-1 in yellow upland soil of southwestern China. The soil P balance and Olsen-P content were significantly (P<0.01) correlated with the annual P application rate. When the amount of average P application was 33.3 kg P·hm-2·a-1, the budgets of soil P balance remained stable, and the application rate of P fertilizer corresponding to the critical value of soil Olsen-P for crop yield was 45.9 kg P·hm-2·a-1. The content of soil Oslen P was mainly affected by the P fertilizer input amount. When the average P application rate was 45.9 kg P·hm-2·a-1, higher crop yield and P fertilizer efficiency would be achieved. When the average P application rate was greater than 45.9 kg P·hm-2·a-1, crop yield showed no response to P fertilizer input, but resulted in a large amount of P surplus in soil, thereby increasing the environmental risk of soil P loss. The long-term application of manure resulted in a higher increase of Olsen-P than the single chemical P ferti-lizer.

[Variation characteristics of maize yield and fertilizer utilization rate on an upland yellow soil under long term fertilization].

An analysis was made on the 16-year experimental data from the long term fertilization, experiment of maize on a yellow soil in Guizhou of Southwest China. Four treatments, i. e. , no fertilization (CK), chemical fertilization (165 kg N x hm(-2), 82.5 kg P2O5 x hm(-2), and 82.5 kg K2O x hm(-2), NPK), organic manure (30555 kg x hm(-2), M), and combined applicatioin of chemical fertilizers and organic manure (NPKM), were selected to analyze the variation trends of maize yield and fertilizer use efficiency on yellow soil under effects of different long term fertilization modes, aimed to provide references for evaluating and establishing long term fertilization mode and promote the sustainable development of crop production. Overall, the maize yield under long term fertilization had an increasing trend, with a large annual variation. Treatment NPKM had the best yield-increasing effect, with the maize yield increased by 4075.71 kg x hm(-2) and the increment being up to 139.2%. Long term fertilization increased the fertilizer utilization efficiency of maize. In treatment M, the nitrogen and phosphorus utilization rates were increased significantly by 35.4% and 18.8%, respectively. Treatment NPK had obvious effect in improving potassium utilization rate, with an increment of 20% and being far higher than that in treatments M (8.7%) and NPKM (9.2%). The results showed that long term fertilization, especially the combined application of chemical fertilizers and organic manure, was of great importance in increasing crop yield and fertilizer use efficiency.