Previous crops

As a general rule, the less closely related the previous crop and the berry species envisaged, the smaller is the risk of transfer of harmful organisms. 

After strawberries no other crops should be grown for at least 3-4 years or, if there has been infection with red root rot (Phytophthora fragariae), at least 15 years. To allow sufficient time for careful preparation of the bed where the strawberries are to be planted, the previous crop should be removed 4-6 weeks before planting. Suitable previous crops are 1-year artificial meadows, oil radish, rapeseed, mustard, buckwheat, winter cereals or vegetables (except Fabaceae). Previous crops that are unsuitable are natural meadows which have been turned over less than 3 years ago (because of weeds, white grubs, wireworms and nematodes), potatoes and tomatoes (because of Rhizoctonia and Verticillium sp.), phacelia (because of rhizome rot) and weed-infested crops. 

Growing an intermediate crop for 1 or 2 years, e.g. oil radish, an artificial meadow with lucerne or another deep-rooting sown plant, improves the 

Application of fertilizers is based on analysis of the soil (taking into account the vigour of the previous crop in the case of new plantings). Soil analyses, which provide information mainly about nitrogen levels, should be carried out at least once every 5 years. To guarantee comparability of the results, it is best to have the analysis always done by the same laboratory. 

Only organic fertilizers can be used in organic farming. To make sure that the nitrogen is available to the plants at the time of greatest need, it is important to take into account the time needed to convert the nitrogen to a form that is available to the plant (speed of action). The speed of action depends on the fertilizer, the soil conditions and the weather. Farm manures can also be used, except for blueberries. Only 10% of the total nitrogen in compost and 50% of that in cattle manure can be included in the nutrient balance in the first year. In the case of other nutrients, 100% is included. 

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There are indications that the variety of C substrates in the rhizosphere soil is basically too wide to be significantly affected by changes in quality of plant residues from the previous crop. For example, legumes as preceding crop were shown to increase significantly microbial diversity in the bulk soil, as estimated by Biolog assay, whereas in the rhizosphere soil this effect of legumes could not be detected (145). 

Rogers CW, Brye KR, Smartt AD, Norman RJ, Gbur EE, Evans-White MA. Cultivar and previous crop effects on methane emissions from drill-seeded, delayed-flood rice production on a silt-loam soil. Soil Sci. 2014 179 28-36. 

A review of the available literature allows a hierarchical ranking of the importance of different factors that influence the pre-harvest infection of cereal grains by Fusarium weather/climate (year) > inoculum pressure/tillage/ previous crop > fungicides > available plant nitrogen. The individual factors related to other fungi are described in separate sections below. 

Inoculum pressure/tillage/previous crop effects on fungal infection and mycotoxin loads... 

Figure 4.14 Changes in labile soil P (extractable with HCOs -form anion exchange resin) during 3 years of wetland rice cropping as affected by timing of tillage (early, late = start, end of fallow), incorporation of previous crop s straw, and application of P (20kgha in NPK plots). The overall P balances over 3 years were +37 and +7kgPha in the NPK plots with and without straw, and —90 and — llSkgPha in the PK plots. DS, WS, dry, wet season DAT, days after transplanting (Bucher, 2001). Reproduced by permission...

Soil treatments Some crops need soil amendments to do well, others make good use of residual fertility left by a previous crop. Grow crops with similar requirements together, so you can apply the appropriate soil treatments for them. This means that all parts of the vegetable area will receive the same treatment over the period of the rotation. 

Members of this family prefer well-drained, relatively fertile soil. Avoid heavy fertilizing, which encourages disease and cuts down on storage life. Soil that has been fed for a previous crop, such as potatoes or brassicas, should suffice. Leeks can benefit from the addition of medium- to high-fertility soil improver in poorer soil. 

Legumes thrive in well-drained but moisture-retentive soil that has been fed for a previous crop, such as potatoes. In a rotation they can... 

Crops in this family all prefer fertile soil that does not dry out easily. They are often included in the "roots" section of a rotation, in soil that has been improved for a previous crop. They may appreciate a mulch of a medium-fertility soil improver on poorer soils. Spinach beet... 

High performance levels for specific crops attained in some situations are often difficult to reproduce even though all recognized conditions are duplicated. There may be answers to some of the unknowns in allelochemicals. Previous crops and soil microorganisms are possible sources of such differences. 

There are numerous reports describing the allelopathic (phytotmicrobial products on crop growth, particularly in conjunction with heavy residues from the previous crop (1-5). The cause of the reduced crop growth has been attributed to the production of a variety of toxic compounds such as phenolic acids, short-chain fatty acids, patulin, and many others (6-9). These compounds may be produced directly or indirectly during the microbial decomposition of organic residues under varying environmental conditions, such as when the soil remains wet over an extended period of time. 

Specific management practices influence triazine runoff and leaching, including fertilizer type, tillage crop residues, and previous crop history, as well as triazine application, formulation, and placement (Baker and Mickelson, 1994). Tillage systems affect various soil properties, such as soil moisture, temperature, pH, organic matter, water flow, and microbial populations, especially at and near the soil surface. These factors can affect transformation, retention, and transport of herbicides in soil. Interactions of and compensations between these processes can influence our prediction of triazine transport in soil. Therefore, triazine movement is usually studied under one management practice at a time. 

The previous crop has a significant effect on weed infestation of strawberry plots. For weed control the soil is either left bare or covered. 

The summer of 1983 provided a rehearsal for the potential doubled CO2 effect. Temperature was above normal and precipitation below normal on scales not unlike those predicted by models of the doubled CO2 effect, or of conditions typical of mid-twenty-first century if other absorbers are included. In 1983 corn yields were halved (by reference to the previous crop year). About half this reduction was probably due to the hostile climate. Winter wheat was adversely affected in some areas, but escaped the worst effects of the summer drought, because of early harvesting dates. Spring wheat was badly affected in many areas. Thus a natural rehearsal of future events appeared to confirm the pessimistic estimates of the Abrahamson forum. 

The second factor that affects the price of safflower is the condition of the market for safflower oil. For example, there may be a surplus of oil from the previous crop, Mexico may be forecasting a large harvest (which occurs 3-4- months before the U.S. harvest), or Japanese buyers may be experiencing a slowdown in their domestic market. 

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