The Latest Technical Guide to Using Boron Fertilizer in Rapeseed Cultivation
Background of Rapeseed Cultivation and Production
In recent years, the rapeseed planting area across Sichuan has shown an upward trend, including the rapeseed planting area in Luzhou, which has also been rising year by year, but the overall area is still very small. The main reasons are low rapeseed yield, poor quality, inadequate production and management techniques, geographical and environmental limitations, and low market economic returns of rapeseed and its processed products, among others. Here, we will only briefly discuss and analyze the problems of low rapeseed yield and poor quality.
The Use of Boron Fertilizer in Agricultural Production
In traditional agricultural production, our concept of fertilizer application is often limited to emphasizing the use of the major elements nitrogen, phosphorus, and potassium, while neglecting the application of trace elements (boron, iron, copper, zinc, manganese, molybdenum, chlorine). However, crop growth and development require these trace elements. If any one trace element is completely absent, crops cannot survive; if one or several are deficient, crops cannot grow normally, with mild cases affecting yield and quality and severe cases possibly resulting in total crop failure.
In addition to the cultivated variety and management level, the rational application of the trace element boron fertilizer is also an important factor affecting the yield and quality of rapeseed. Rapeseed is a crop highly sensitive to boron fertilizer. Once boron is deficient, the typical “flowers but no seeds” symptom appears, with low seed-setting rate, few pods, and poor quality. Boron deficiency also causes slow green-up and low survival rate when transplanting rapeseed, poorly developed root systems at the seedling stage, yellowing or purplish-brown leaves, high branching nodes, few branches, clustered branches, and induced clubroot disease, stem cracking, and lodging in the middle and late growth stages, seriously affecting the yield and quality of rapeseed.
Analysis of Currently Marketed Boron Fertilizer Products
The boron fertilizer products currently on the market are mainly borax and a small amount of borate. Borax is used more widely, mainly because it is cheap. However, borax has a very low pure boron content, many impurities, poor crop safety, poor solubility, and low crop absorption and utilization rate. Borax is mainly applied as a base fertilizer. Boric acid, on the other hand, has a high pure boron content, good solubility and absorption, and high safety, and is mainly used for foliar spraying. The reason for its relatively low usage is mainly the high price of boric acid. However, based on a comprehensive consideration and analysis of boron fertilizer quality, safety, and yield- and income-increasing effects, boric acid is recommended.
Boron Fertilizer Application Techniques for Rapeseed
According to the characteristics of rapeseed's boron fertilizer requirements at each growth stage, boron fertilizer is mainly applied during the following key periods:
After transplanting and survival at the seedling stage: borax 200-300 grams per mu, mixed evenly with 5 kilograms of fine soil or river sand and applied separately, or mixed evenly with nitrogen, phosphorus, and potassium chemical fertilizers and applied to the field;
Bolting stage: spray the leaves with a 1500-fold dilution of polyboron.
Early flowering stage: spray the leaves with a 1500-fold dilution of polyboron.
Note: Do not apply boron fertilizer more than 2-3 times, do not increase the dosage or concentration at will, and when applying it as a base fertilizer, an appropriate amount of lime can be added and mixed in together.