Crop yield

In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields.

Innovations, such as the use of fertilizer, the creation of better farming tools, new methods of farming and improved crop varieties, have improved yields. The higher the yield and more intensive use of the farmland, the higher the productivity and profitability of a farm; this increases the well-being of farming families. Surplus crops beyond the needs of subsistence agriculture can be sold or bartered. The more grain or fodder a farmer can produce, the more draft animals such as horses and oxen could be supported and harnessed for labour and production of manure. Increased crop yields also means fewer hands are needed on farm, freeing them for industry and commerce. This, in turn, led to the formation and growth of cities, which then translated into an increased demand for foodstuffs or other agricultural products.

Measurement

The units by which the yield of a crop is usually measured today are kilograms per hectare or bushels per acre.

Long-term cereal yields in the United Kingdom were some 500 kg/ha in Medieval times, jumping to 2000 kg/ha in the Industrial Revolution, and jumping again to 8000 kg/ha in the Green Revolution. Each technological advance increasing the crop yield also reduces the society's ecological footprint.

Yields are related to agricultural productivity, but are not synonymous. Agricultural productivity is measured in money produced per unit of land, but yields are measured in the weight of the crop produced per unit of land. A farmer can invest a large amount of money to increase his yields by a few percent, for example with an extremely expensive fertilizer, but if that cost is so high that it does not produce a comparative return on investment, his profits decline, and the higher yield can mean a lower agricultural productivity in this case. A yield is a 'partial measure of productivity', because it may fail to accurately measure the actual productivity of the farming operation by not including the totality of the inputs.

Seed multiplication ratio

The seed multiplication ratio is the ratio between the investment in seed versus the yield. For example, if three grains are harvested for each grain seeded, the resulting multiplication ratio is 1:3, which is considered by some agronomists as the minimum required to sustain human life. One of the three seeds must be set aside for the next planting season, the remaining two either consumed by the grower, or for livestock feed. In parts of Europe the seed ratio during the 9th century was merely 1:2.5, in the Low Countries it improved to 1:14 with the introduction of the three-field system of crop rotation around the 14th century.

Seed multiplication ratio is variable, subject to several factors. Agricultural improvements can raise the ratio, and revisions were recommended in 2018 by the Indian Council of Agricultural Research.

Law of physiological relations

Alexander Mitscherlich studied crop yields in 1909 and articulated a "law of physiological relations". It was compared to the law of diminishing returns in 1942, when Liebig's law of the minimum and the limiting factors of Frederick Blackman were also noted:

Liebig's Law of the Minimum was the formulation of an idea that yield of a crop was determined primarily by the amounts of plant food that were present in minimum quantities. His idea was discussed later as the Limiting Factor by BLACKMAN and again by MITSCHERLICH as the Law of Physiological Relations. The latter was expressed as a logarithmic function between yield and the quantity of plant food constituents, which is virtually the Law of Diminishing Returns.

The relation was reviewed by Hans Schneeberger in 2009.

Data

The below table shows the irrigated (as opposed to rainfed) yield in both metric (Metric System; SI) and customary units (Imperial System; still used in USA; conversion rate is 67.2511 kilograms per hectare in 1 bushel per acre), related comments, time from plant to harvest, and water required. Note that these are estimates based on available data and general knowledge as of 2022. Actual values can vary depending on various factors like farming practices, region, soil type, climate, etc. "Relative Units" indicates the column is only meaningful for intracolumn comparisons (i.e. only useful for comparing values from within that column to approximate rank).

Crop	Irrigated Kg-per-Hectare Yield (low)	Irrigated Kg-per-Hectare Yield (high)	Irrigated Bushel-per-Acre Yield (low)	Irrigated Bushel-per-Acre Yield (high)	Irrigated Yield (comment)	Average Yield Time in Months (low)	Average Yield Time in Months (high)	Average Water In Relative Units Required Per Yield
Rubber	Varies based on tapping frequency	Varies based on tapping frequency	Varies based on tapping frequency	Varies based on tapping frequency		60	84	180
Sugarcane	60,000	80,000	892	1190		12	18	1500
Tomatoes	40,000	80,000	595	1190		2	5	70
Potatoes	35,000	50,000	520	743		2	5	250
Cassava	20,000	40,000	297	595		8	12	400
Pineapples	20,000	60,000	297	892		12	24	500
Bananas	15,000	30,000	223	446		8	15	220
Avocados	10,000	20,000	149	297		12	18	600
Maize (Corn)	8,000	12,000	119	178		3	4	500
Rice	6,000	8,500	89	126		3	6	1200
Grapes	5,000	10,000	74	149		3	36	400
Wheat	5,000	8,000	74	119		4	8	650
Barley	4,000	6,000	59	89		4	6	580
Olives	3,500	7,000	52	104	in oil	36	48	800
Sorghum	3,000	5,000	45	74		3	5	450
Oil Palm	3,000	5,000	45	74	in oil	36	48	1500
Soybeans	2,500	4,500	37	67		4	5	450
Walnuts	2,500	5,000	37	74	in shell	24	36	1000
Oats	2,500	5,000	37	74		4	6	no estimate available
Coconuts	2,000	5,000	30	74		72	120	1200
Rapeseed (Canola)	1,500	2,500	22	37		3	4	no estimate available
Flax seed	1,200	2,000	18	30		4	5	no estimate available
Sunflower	1,000	2,500	15	37		3	4	400
Groundnuts (Peanuts)	1,000	3,500	15	52		4	5	no estimate available
Cotton	1,000	2,500	15	37	in lint	5	7	700
Peanuts	1,000	3,500	15	52		4	5	250
Hemp Seeds	600	1,500	9	22		3	4	no estimate available
Beans	500	3,000	7	45		2	4	150
Millets	500	2,000	7	30		3	4	350
Lentils	500	1,500	7	22		3	4	150
Cocoa	500	1,000	7	15	in dried beans	5	6	1200
Coffee	500	1,500	7	22	in dried beans	6	8	1400
Chia Seeds	400	1,000	6	15		4	6	no estimate available
Sesame	400	800	6	12		3	4	250

See also

• Actual Production History
• Agricultural productivity
• Grain yield monitor
• Green Revolution
• Yield (wine)