In which regions of our country is red loam distributed, and what crops is it suitable for growing?
Red loam is a zonal soil formed under the hot and humid climate of the southern subtropics through a relatively strong ferrallitic process. Its intensity of ferrallitization, soil nutrients and acidity fall between those of red earth and lateritic red earth. The regions where red loam is distributed and what crops it is suitable for growing are what many people want to know.
Red loam has a very high clay content and a heavy texture, but because of the aggregates formed by iron oxide and aluminum oxide colloids, the soil permeability is still fairly good and waterlogging is not serious; because of the high degree of weathering, the soil is strongly acidic, with a pH of around 5.0, and is poor in plant nutrients. Red loam supports evergreen monsoon forest, mainly including schima, banyan, and elaeocarpus, with a ground cover mostly of ferns.
In which regions of our country is red loam distributed?
In our country, red loam is distributed on both sides of the Tropic of Cancer (south of the Nanling Mountains to the northern section of the Leizhou Peninsula), at a relatively low latitude, with high mountain barriers on the north and northwest sides and the sea on the southeast side; in summer the warm, humid air currents from the ocean prevail, while in winter the dry, cold air masses from the interior are mostly weakened by the obstruction of the high mountains, thus forming excellent climatic conditions of warm winters and hot summers with abundant moisture and rain, a rare natural greenhouse within the same climatic zone.
In the southern subtropical monsoon climate zone, the average annual temperature is 19-22°C, the average temperature of the coldest month is 10-15°C, the average temperature of the hottest month is 21.7-28.5°C, and the accumulated temperature of ≥10°C is mostly 6500-8450°C. The annual precipitation is 1000-2600 mm; the annual evaporation is 1376-2000 mm. The frost-free period reaches 350 days. The dry and wet seasons are distinct, generally March to September being the rainy season and October to February the dry season. The annual aridity is 1.32-0.37. Because the red loam distribution area spans 3 degrees of latitude, and because the terrain is complex, the regional differences in climate are fairly obvious.
The primary vegetation of the red loam region is southern subtropical monsoon forest, and the vegetation composition contains both tropical rainforest elements and relatively many subtropical plant species and genera. The existing vegetation structure trend in the red loam region is that tropical species and genera increase from north to south and from east to west. On the coastal hills and platforms of Guangdong and Fujian, the primary vegetation has been almost completely destroyed and can only be seen in well-preserved feng shui woods and nature reserves. The main tree species composing it include: red castanopsis, Castanopsis uraiana, red-scaled syzygium, thick-shelled cinnamon, hard-shelled cinnamon, various elaeocarpus species, various holly species, yellow engelhardtia, yellow tung, hairy adina, olive, and scattered Schefflera, various Adina species, sarcosperma, dog-bone firewood, and Lindera metcalfiana, etc. The understory shrubs include ardisia, psychotria, fish-scale herb, various litsea species, five-month tea, Baphicacanthus cusia, and Lasianthus, etc. The herbaceous layer mainly includes the shade- and moisture-tolerant, low-growing single-leaf pronephrium, lophatherum, wild ginger, chain fern, golden hair dog fern, tree fern, brake fern, sarcandra, golden chestnut orchid, taro, and mountain banana, etc.
The parent material types of red loam are diverse. Soil development and fertility characteristics are deeply affected by the parent material. The general trend is that from east to west, the magmatic rock component decreases while the sedimentary rock component increases.
What is red loam suitable for growing?
The fruit trees suitable for growing in the red loam region include longan, lychee, sugarcane, carambola, banana, and mango, etc. Medicinal herbs can also be grown, such as polygonum multiflorum, eucommia, reishi, and notoginseng, etc. Field crops can be grown two to three times a year, and this is a production area for winter vegetables in our country.
The geographical location of red loam has relatively favorable biological and climatic conditions. Apart from the existing cultivated land, which should still be strengthened with fertilization and protective planting measures, the large-area red loam resources of hills and mountains have the advantage of developing tropical cash crops, with great production potential. In development and utilization, a holistic approach should be taken, implementing regional planting, focusing on tropical and subtropical fruits, and according to different ecological environments and soil conditions, establishing various high-quality fruit commodity bases so as to quickly form flagship products for the international market.
In soil improvement, the focus should be on solving the two major problems of drought and barrenness. Red loam soils are often severely eroded, with thin soil bodies, poor site conditions for forest trees, less biological accumulation than the previous two subtypes, and relatively low fertility; in development and utilization, closed-hill afforestation should be adopted to restore vegetation and control soil erosion.
On this basis, fuelwood forests of barren- and drought-tolerant masson pine, big-leaf acacia, and black pine should be established. In sections with locally deep soil bodies, orchards can be reclaimed to develop fruits such as bayberry, emblic leafflower, and pineapple; but water and soil conservation engineering should be strengthened, building high-standard fish-scale pits and level terraces, combined with interplanting in young orchards, promoting no-till methods, increasing ground cover, and preventing water and soil loss in orchards; increasing the application of organic fertilizer and mineral fertilizer to regulate the soil nutrient balance.