Nongyan 農諺 "farmers' proverbs" is a literary genre of proverbs or rules on agriculture, similar to European "weather lores". Agricultural proverbs are the means by which farmers passed down their konwledge about agricultural methods by word of mouth and from generation to generation in a concise, vivid, short language. The Han-period 漢 (206 BCE-220 CE) dictionary Shuowen jiezi 說文解字 therefore explains the word yan 諺 as "words of transmission" (chuan yan 傳言).
The origin of Chinese agricultural proverbs goes back to earliest times. The oldest rules for agricultural activities can be seen in the Confucian Classic Shijing 詩經 "Book of Songs", particularly the songs Qiyue 七月 "In the seventh lunar month", Putian 甫田 "Extensive fields", Datian 大田 "Large fields" or Chenggong 臣工 "Ministers and officers" in particular. Other descriptions of farming activities are found in a genre called yueling "monthly ordinances", as found, in Xia xiaozheng 夏小正 or Simin yueling 四民月令. An old collection of farmer's proverbs, Cui Shi's 崔寔 (d. 170 CE) Nongjiayan 農家諺, is only preserved in fragments.
The book Fan Shengzhi shu 氾勝之書 in the 1st century BC and the Qimin yaoshu 齊民要術 from the 6th century CE have included many agricultural proverbs. Sayings such as "An acre is not [necessarily] better than a rood" (qing bu bi mou shan 頃不比畝善) or "To how three inches deep will preserve moisture" (chutou san cun ze 鋤頭三寸澤) are still popular in some areas.
Some of the commonest sayings can be found in ancient sources like Yantielun 鹽鐵論 (ch. 14 Qingzhong 輕重) or Daodejing 道德經 (ch. 23), like "grass does not grow under a shady tree, and rocks cannot make fertile grounds" (mao lin zhi xia wu feng cao, da kuai zhi jian wu mei miao 茂林之下無豐草，大塊之間無美苗, modern form dashu zhi xia wu feng cao, da kuai zhi jian wu mei miao 大樹之下無豐草，大塊之間無美苗) or "strong wind cannot last until dawn, heavy rain will not last the whole day" (piaofeng bu zhong chao, zhouyu bu zhong ri 飄風不終朝，驟雨不終日, modern form zhouyu bu zhong ri, jufeng bu zhong chao 驟雨不終日，颶風不終朝). The proverb "if the root tips are white on the solar term Limit of Heat, the farmer is terrified" (chushu gentou bai, nongfu chi yi he 處暑根頭白，農夫吃一嚇) is first mentioned in the agricultural treatise Shenshi nongshu 沈氏農書, and the saying "an inch-long wheat shoot isn't afraid of a foot of water, but a foot-long wheat plant fears an inch of water" (cun mai bu pa chi shui, chi mai zhi pai cun shui 寸麥不怕尺水，尺麥只怕寸水) originates in the technical book Tiangong kaiwu 天工開物. The sayings "no ash, don't plant wheat" (wu hui bu zhong mai 無灰不種麥), and "wheat harvest is like deleting fire" (shou mai ru jiu huo 收麥如救火) are recorded in the book Bianmin tuzuan 便民圖纂. The prognostication book Tianjia wuxing 田家五行 mentions the proverb "if the sixth lunar month is not hot, the ears will have not seeds" (liu yue bu re, wu gu bu jie 六月不熱，五穀不結). "If you want wheat, wait for the third snowy day" (ruo yao mai, jian san bai 若要麥，見三白) is quoted in Chaoye qianzai 朝野僉載, and the recommendation "if you want to know the five grains, first learn from the five types of trees" (yu zhi wu gu, dan shi wu mu 欲知五穀，但視五木) is given in the farming book Qimin yaoshu.
Many ancient books on farming quote from such sayings, introducing them with the words "the people in old times used to say" (gu ren yun 古人云) or "a proverb says" (yan yun 諺云).
Fei Jiexin's 費潔心 book Zhongguo nongyan 中國農諺 (Shanghai: Shanghai Shudian, 1937) was compiled in a process of the collection of more than 100,000 proverbs from all over China. From this vast treasure, some 30,000 were selected and included in the book. They can be divided into categories like proverbs concerning crops; methods and measures; animal husbandry and sideline production like forestry and fishing; weather; and village life. Those on agricultural produce again can be divided into food crops, economic crops (like cotton, hemp, tobacco or tea) and crops of garden culture (fruits, legumes, flowers). Proverbs on methods in agriculture concern the topics soil treatment or types of soil, fertilizers, irrigations, harvesting, weeding or farming tools).
One of the characteristics of Chinese agricultural proverbs is that they have a strong regionality which is consistent with the strong regionality of agricultural production. For example, a proverb from Shaanxi says: "When the wheat is yellow, bring out sticky rice for congee; if sticky rice is yellow, bring out wheat" (mai huang zhong mi, mi huang zhong mai 麥黃種糜，糜黃種麥), while a similar proverb from the province of Zhejiang stipulates the same for wheat and hemp (mai huang zhong ma, ma huang zhong mai 麥黃種麻，麻黃種麥). The suitable time for wheat sowing in North China is "from the solar term White Dew to Cold Dew" (bailu zao, hanlu chi 白露早，寒露遲), but the best time was the autumn equinox (qiufen 秋分)", while in the province of Zhejiang it is "from Cold Dew to Winter Arrives" (hanlu zao, lidong chi 寒露早，立冬遲), but the best time is just around the solar term Frost Descends (xiangjiang 霜降). Regarding sesame and millet North China qualifies for "sesame at the solar term Grain Starts Filling (xiaoman 小滿 and wheat at Grain in Ear (mangzhong 芒種)", while Zhejiang farmers had the proverb "first sow sesame, thereafter millet" (tou fu zhima, er fu su 頭伏芝麻二伏粟). The above-mentioned proverb with the spade, originating in northern China, is different in the south. While in north China, it was generally required during dry period to loosen the soil, but urgently necessary in south China during periods of draught in order to cut off micro-canals of evaporation. For this reason, the proverb is slightly different in the south, and goes "If drought arrives, a spade will bring water" (Han lai chutou hui sheng shui 旱來鋤頭會生水). Another difference between south and north is the term gu 穀 "grain", which denotes millet in the north, but rice in the south.
The third characteristic of Chinese proverbs on farming is the influence of the historical background. Farming proverbs such as "people are afraid of getting poor when old, rice is afraid of drought in autumn" (Ren pai lao lai qiong, dao pa qiu lai han 人怕老來窮，稻怕秋來旱) or "When the sixth lunar month arrives, sell your quilts and buy ash (as fertilizer) for it" (Liu yue dao, mai mian bei, mai hui liao 六月到，賣棉被，買灰料), reflect the precarious life of farmers in ancient times.
Farmers in ancient times observed the starry constellations, determined the appropriate time of farming activities by taking into considerations the condition of soil and weather. Regarding the sowing of wheat, for instance, was the rule to bring out the seeds as long as the constellation Shen was still visible (Shen bu luo, zhi guan zhong 參不落，只管種). This is still the standard rule for the wheat sowing period in the Yellow River region. Maize and sweetpotatoes were only imported from overseas during the Ming period, whereafter a large number of agricultural proverbs have been created to spread more knowledge about the cultivation techniques of these two non-endemic crops. For example, "when cutting the head of maize, it will grow as strong as an ox" (yumi qu le tou, liqi da ru niu 玉米去了頭，力氣大如牛). The rule "Straight planting in mountain fields, oblique planting in moist fields" (Shanyuan zhi cha, tangyuan xie cha 山園直插，蕩園斜插) means that the soil moisture in mountainous areas is low, and sweetpotato seedlings should be planted vertically and inserted deeply. The soil moisture in lowland fields was sufficient to allow for shallow insertion and oblique direction. These proverbs show the intricate knowledge of the peasantry about various needs for the cultivation of plants. Another example for technical issues is the proverb "ox dung is cold, and horse dung is hot" (niu fen leng, ma fen re 糞冷，馬糞熱) which follows the observation that different types of manure have different effects on fertility.
The collector and editor Ma Guohan 馬國翰 (1794-1857) compiled a brief book of farmer's saying, Nongyan 農諺, which quotes a variety of ancient books and was published in 1843 and revised in 1889 by Li Yuanjin 李元璡.
Because agricultural proverbs were passed down orally, the language is brief and close to everyday language, and easy to memorize. Many agricultural proverbs appear as very simple matters of course, but in fact contain profound principles of biology and nature. By studying agricultural proverbs, it is possible to acquire technical knowledge of agricultural production and to obtain numerous valuable information of farming methods.