Maize yield and nitrogen-use characteristics were promoted as consistently improved soil fertility: 6-year straw incorporation in Northeast China

Long-term impacts of straw incorporation on soil fertility, and maize production and nitrogen (N) use status had not been thoroughly investigated in Northeast China, the most vital agricultural base across the nation. We conducted a consecutive 6-year field experiment, including straw amendment at 4 000, 8 000 and 12 000 kg/ha, and no straw incorporation was set as the control. Our experiment confirmed that the grain yield and crop N uptake in straw treatments were raised due to consistently improved soil fertility indices (associated with soil N cycling), and larger straw addition generally exerted more profound influences. Boosted nitrogen harvest index (NHI) indicated that nitrogen use efficiency (NUE) was gradually enhanced if applying more straw. More specifically, greater straw amendment caused higher N recovery efficiency from straw N, even though the N recovery efficiency of accumulated N addition declined accordingly (considering fertiliser N besides straw N). Thus, these trends suggested that more efficient utilisation of straw N by crop was the probable reason for elevated NUE over multi-year time series. Our research offered helpful insight to optimally employ straw incorporation and N fertilisation for coordinating agricultural sustainability and environmental protection.

Repeated Application of Rice Straw Stabilizes Soil Bacterial Community Composition and Inhibits Clubroot Disease

Straw amendment can improve soil properties and is an effective strategy to control soil-borne diseases. However, gramineous straw application to vegetable fields has rarely been studied. In this study, rice straw was added to the field of Chinese cabbage for one or two years (repeated), and Chinese cabbage plant growth, disease occurrence and changes in soil chemical properties were measured. In addition, the bacterial community composition of Chinese cabbage was analyzed using Illumina MiSeq sequencing. Results showed that rice straw application increased the content of available nutrients, pH and electrical conductivity, but decreased the diversity and richness of the bacterial community. The relative abundances of Acidobacteria and Chloroflexi were increased after repeated rice straw application, which were associated with the available potassium and pH in the soil. Network analysis revealed that rice straw amendment differentially affected the key bacterial genera. These results suggest that repeated application of rice straw changed the soil chemical properties and altered the bacterial community composition to suppress the clubroot disease incidence in Chinese cabbage.

Pyrolysis Improves the Effect of Straw Amendment on the Productivity of Perennial Ryegrass (Lolium perenne L.)

The use of straw as a soil amendment is a well-known and recommended agronomy practice, but it can lead to negative effects on the soil and crop yield. It has been hypothesized that many problems related to the burying of straw can be overcome by pyrolyzing it. The objective of this study was to determine the effect of straw and its biochar on the biomass production of perennial ryegrass. A pot-based experiment was conducted with three factors: (i) the crop species used as feedstock, (ii) raw or pyrolyzed organic material, and (iii) the rate of organic amendments. The soil in the pots was amended with straw and biochar produced from Miscanthus (Miscanthus × giganteus) or winter wheat (Triticum aestivum L.). After soil amendment application, perennial ryegrass (Lolium perenne L.) seeds were sown. During two years of the experiment, the perennial ryegrass above-ground biomass production and root biomass and morphology parameters were determined. Straw and biochar resulted in higher perennial ryegrass above-ground biomass compared with that of the non-fertilized control. However, straw amendment resulted in lower plant yields of above-ground biomass than those of the biochar treatments or the mineral fertilizer control treatment. The feedstock type (Miscanthus or wheat) significantly affected the perennial ryegrass yield. No difference was observed among wheat and Miscanthus biochar, while among straws, Miscanthus resulted in lower perennial ryegrass productivity (the higher rate of straw and biochar as soil amendments resulted in relatively high perennial ryegrass productivity). The organic amendments resulted in relatively high root biomass and length. The root:shoot ratio was lower in the treatments in which biochar was used, whereas feedstock species and amendment rate were not statistically significant for any of the root biomass and morphometric parameters. The results suggest that the use of pyrolyzed straw can be a reliable strategy instead of straw, increasing ryegrass growth and productivity.

The Effect of Different Organic Fertilizers on Yield and Soil and Crop Nutrient Concentrations

At present, organic fertilizers are not widely used in intensive arable agriculture, and not much is known about their effects on crop nutrition. In a field experiment at Rothamsted, UK, anaerobic digestate (AD), compost, farmyard manure (FYM), straw, and mixes of amendment + straw, were applied at: 1, 1.75, 2.5 or 3.5 t carbon ha−1, with all plots receiving the same input of mineral fertilizer. After five seasons of application, plots receiving non-straw amendments had greater straw and grain yield of 28% and 18% respectively, and plots receiving the highest amendment rate had a 37% higher straw and 23% higher grain yield, compared to control plots. Whereas, the straw-only amendment did not increase yield compared to the control. The concentrations of secondary and micro nutrients in the crop, particularly P, Ca, and S in the straw, and P and Fe in the grain, were significantly greater in the crop receiving non-straw amendment compared to the control. Interestingly K, Fe, and Zn were greater in the crop straw treated with the straw-only amendment. Therefore ‘biomass dilution’ of secondary and micro nutrients did not occur in the higher-yielding amended plots after five seasons, and organic fertilizers would improve the quality of high-yielding, intensively produced crops. The study also demonstrates that portable x-ray fluorescence (pXRF) could be a reliable, cost-effective tool for screening potential organic fertilizers.

Maize production and field CO2 emission under different straw return rates in Northeast China

In order to understand and clarify the impacts of straw return on maize production and field CO₂ emission in Northeast China, the most important agricultural base of the nation, a field experiment was conducted in 2012–2015, including no straw return (CK), straw amendment at 4000 kg/ha (S₄), and at 8000 kg/ha (S₈). The average grain yield was found significantly promoted by the two straw treatments, with comparably increased magnitudes of 11.0% and 12.8% for S₄ and S₈, respectively, and the benefits were gradually enlarged with increasing experimental duration. Although straw return tends to reduce slightly the harvest index, it was detected that it exerted significantly positive impacts on nitrogen harvest index. These results implied that added straw could lead to raising grain yield and enhancing nitrogen use efficiency simultaneously. In 2015, our monitoring showed that CO₂ emission was elevated with intensified use of straw, and S₄ and S₈ decreased carbon emission efficiency by 7.3% and 13.6%, respectively. However, there was no statistical difference between S₄ and CK. Overall, straw addition at the rate of 4000 kg/ha accompanied with inorganic fertilizer was recommended to be adopted in Northeast China, which was considered as a sustainable and relatively environment-friendly agricultural technique during maize production.